Event and User count lower than the actual number

I’m trying to understand what could be causing the Event and User count for certain events to be different from the total number of users when opening each single event.

We are running the 9.1.2 self-hosted version of Sentry.

Here is a screenshot showing:

  • in the top right part 13 events and 13 users
  • a list with 15 events

All of the events have a different user so both the number of events and users should be 15.

I saw the other threads mentioning the cron workers (e.g. Wrong events count in issues list) but our workers have been up and running with no issues for the past month.

Any ideas about what to look for is greatly appreciated.