This is one of the most common questions after installing a Cookie Banner.
The short answer: in most cases, it is not an error. This is the expected behavior of AdOpt when complying with data protection laws and functioning as intended.
Before AdOpt, Google Analytics, Meta Pixel, and other Tags that collected visitor data would fire for 100% of your audience without asking for permission.
When the AdOpt Cookie Banner is correctly configured with the Third-Party Tag Blocking, these Tags only collect data from visitors who give their consent — and this is exactly the difference that appears as a “drop” in reports.
💡 Tip: Before investigating anything, compare your banner acceptance rate (available in AdOpt Analytics) with the size of the drop you observed in Google Analytics. If the figures are similar, this is expected behavior.
What is actually happening
When AdOpt is installed with Tags inactive by default enabled, analytics and marketing Tags remain paused until visitors provide explicit consent through the AdOpt Cookie Banner.
Only Tags marked as necessary continue to function without requiring consent.
This means that visitors who:
- reject cookies,
- close the banner without making a choice,
- or leave the website before making a decision,
are not counted by analytics tools connected through a Tag Manager. They can still browse the website normally — they simply do not appear in Google Analytics, Meta Ads, or Clarity reports.
The most common causes, ranked by impact
1. The acceptance rate is never 100%
Even when AdOpt is configured perfectly, some visitors will always reject or ignore the Cookie Banner. The math is simple: if 30% of visitors do not consent, Google Analytics will no longer capture those same 30%.
2. Google Consent Mode (basic or advanced)
If Google Consent Mode v2 (GCM v2, CoMo) is enabled in basic mode, Google only collects data from visitors who have consented — no exceptions.
In advanced mode, Google receives anonymous signals even from visitors who reject consent and can **statistically model** much of the data that would otherwise be lost.
Switching from basic to advanced mode often recovers most of the difference.
ℹ️ Info: Learn how to configure GCM advanced mode: 🔗 Google Consent Mode Activation.
3. Script installation order
The AdOpt script must load before** Google Analytics Tags so that consent is applied correctly from the very first moment.
In Google Tag Manager, this means using the Consent Initialization - All Pages trigger for the AdOpt Tag (which always fires first) and the Initialization - All Pages trigger for the GA4 configuration Tag.
If the order is reversed, data inconsistencies may occur, including traffic classified as "not set".
4. Different measurement methodologies
AdOpt counts unique visitors by Cookie ID (a new Cookie ID = a new visitor).
Google Analytics counts users based on User-ID or Device-ID, combined with statistical modeling when advanced GCM is enabled, depending on the property's Reporting Identity setting.
Because each tool measures visitors differently, the numbers will never match 100%, even when there are no technical issues.
ℹ️ Info: Learn how AdOpt calculates unique visitors and total visitors in 🔗 Analytics: Understanding Your Cookie Banner Numbers.
Does this also explain "(not set)" in Google Analytics?
Partly. "not set" under Source/Medium often appears when the session_start event does not fire correctly — for example, when Google Consent Mode is in basic mode and completely blocks the Tag before it can capture the visitor's source.
Checking whether advanced Google Consent Mode is enabled is the first step toward reducing this issue.
How can you confirm that everything is working correctly?
1. Access the AdOpt dashboard and enable Installation Verification for your banner.
2. Use Google Tag Assistant to check whether the consent event appears correctly in your container's debug view.
3. In an incognito window, open the browser console, type `dataLayer`, and check whether `analytics_storage` changes from `denied` to `granted` after you accept cookies.
If all three steps work as expected, Google Consent Mode is active, and the observed drop is a natural result of consent choices — not an installation failure.
Frequently asked questions
Does a drop in visitors mean there is an issue with AdOpt?
In most cases, no. A drop in recorded visitors may be related to user consent: when a visitor rejects cookies or does not interact with the Cookie Banner, certain information may no longer be collected by analytics tools, depending on Tag configuration and the consent rules in place. This behavior may be expected in an implementation designed to comply with Brazil's LGPD data protection law.
However, the drop may also have other causes, such as changes in website traffic, marketing campaigns, or analytics tool settings.
If the Google Analytics Tag is categorized as **necessary** and correctly installed, the drop in visitors may be caused by factors unrelated to the Cookie Banner or AdOpt Tag installation.
Examples of external factors that may influence these numbers:
- Changes in organic traffic: Changes in the website's search engine rankings or updates to Google's algorithms may reduce the number of visitors.
- Marketing campaigns: The end of paid campaigns, reduced advertising spend, or changes in promotional strategies may decrease traffic.
- Seasonality: Holidays, special occasions, and changes in demand for products or services may affect traffic volume.
- Website changes: Changes to the code, page loading behavior, or analytics tool implementation may affect data collection.
- Analytics tool settings: Changes in Google Analytics, Google Tag Manager, or consent rules may affect how visits are recorded.
- Browser blockers and restrictions: Extensions, privacy settings, and browser protection mechanisms may prevent certain data from being collected.
What is the difference between basic and advanced Google Consent Mode?
In basic mode, Google only collects data from visitors who have accepted cookies. In advanced mode, Google receives anonymous signals even from visitors who reject consent and can statistically model some of the missing data, bringing reports closer to the actual figures.
Why does Google Analytics show different numbers from AdOpt?
Each tool uses its own method to count visitors. AdOpt uses Cookie ID; Google Analytics uses User-ID or Device-ID, combined with statistical modeling depending on the property's Reporting Identity settings. Differences of 10% to 30% between the two tools are normal.
Do I need to configure anything special in Google Analytics?
It is not mandatory, but we recommend reviewing the Reporting Identity setting (Admin > Property Settings) and considering **Observed** mode, which displays only actual data without modeling — useful for comparing figures with AdOpt.
Does Google Signals affect these numbers?
No longer. Since February 2024, Google has removed Google Signals from the Reporting Identity options. It now only supports advertising audiences and demographic data — it does not affect visitor counts.
Is a drop in visits necessarily bad for my website?
Not necessarily. A drop in recorded visits does not, by itself, mean that your website is receiving fewer people or performing worse.
When a visitor rejects cookies or does not interact with the Cookie Banner, certain information may no longer be collected by analytics tools, depending on Tag configuration and the consent required. As a result, some visits may no longer appear in reports.
In this scenario, your data may better reflect the visitors who consented to data collection, making your analysis more representative of that audience.
In addition, the **conversion rate increases** when the number of recorded visits decreases, even if the number of conversions remains stable. This happens because the rate is calculated based on the relationship between conversions and recorded visits.
For this reason, it is important to analyze other metrics together, such as the number of conversions, the conversion rate, and traffic trends over time, before concluding that website performance has declined.