Hi !
Our traffic decreased since 21st March while GA4 is increasing. We’ve made the two updates :
- 4.14.0 at 8h37 on march 21st,
- 4.14.1 à 9h44 on march 22nd
We used to measure our traffic with 2 tools :
- Matomo (on-premise) : to get all the data with or without cookie consent,
- GA4 : to manage specifically our ads.
Normally, we always get 60-68% cookie opt-in, so there is difference of 33% between Matomo and GA4 audiences.
So, since 21st March, GA4 traffic is higher than Matomo :
In the same time, if we focus on Organic Search, we also find abnormal traffic drop on 21st March on Matomo while there is no drop on GA4 while our search console KPIs are increasing.
Any other informations to help :
- DoNotTrack is not enabled,
- Before march 21st Matomo was recording a lot more visits than ga4, and after it records less visits, the traffic drop in 1 day only,
- No change about javascript code tag,
- We’re not using tracking spam prevention plugin,
- No error in our log server.
Hope someone could help us 
Thank you,
Lucas