If you see a major difference between the Media Spending and the Effective Media Spending in your Media activity dashboards, this might indicate an issue with either ad-ids not properly set up (for Meta) and/or issues with Google if you have multiple accounts for several countries.

We consider a big gap to be more than 70% of difference between the Media Spending and the Effective Media Spending.

To fix this issue, make sure your UTMs are properly set up with ad-Ids (learn how on this page, section "For paid media with an Ad Manager"). If you have multiple Google Ads accounts for several countries, please visit this page, in the section "If you have multiple Google Ads accounts".