Hello everyone and thanks you for your support 
We (a website with around 2 millions visites by month) recently switch from GA4 to Matomo.
And I discovered that our implementation of Matomo does not separate well the different users and too many different actions are associated to the same users, when I am convinced that they are different users.
Indeed, several findings corroborate this observation:
- In several analyzed visits, there are inconsistent action sequences (user creating an account 2 minutes after logging in).
- Most of our Android users are visiting on several different phones (while we do not send any internal ID to Matomo to recognize them across devices).
- Our number of visitors and sessions has decreased by 2 thirds while the number of page views and events remains constant.
- The number of visite by user increased a lot.
- Our engagement time has largely increased, without any change in the site.
We use _pk_id cookie to identify visitor and we don’t transmit any internal userId to recognize users across devices.
Have you ever encountered this problem on sites with a lot of traffic? Are there any pitfalls to avoid in the Matomo configuration that could cause this?
Thanks you for your help.
Quentin