However, I believe some filewalkers (the trash one for example and perhaps TTL collector are still working with a normal priority).
That’s usually mean that the collected stat was not written to the databases. So you need to figure out why. I believe you have errors, related to the databases (malformed, “database is locked”, “file is not a database”, etc.).
If you also have errors, related to a used-space-filewalker, then the databases will not be updated too. As a result - “reset” stat on the dashboard (to what is it stored in the databases).