We too have this issue. Since July 2021 lots of devices filling up. Have done multiple resets. Advise from our support is to change the setting to clear up profiles on sign out even though googles advise is not to.
I guess we can only wait until google release another update to maybe fix the issue. The setting to clear up is not really practical. Apps download on each login again. Not an issue for schools with fast internet, But the ones with slow speeds, this will cause issues.
It is not only managed devices, a user in our workplace uses a Chromebook as a standalone and they have also reported issues since the summer.