Completely delete a device from synching

[wehkah]

Hello,

there's a small problem bugging me, and I'd appreciate if someone could help me with this. At home, I like using my "old" Pixel 4 for listening to podcasts for its excellent sound quality. But it doesn't synch very well with Nextcloud/Gpodder: listening status is inaccurate, some podcasts appear twice with different counts of "new" episodes, and other glitches. Even a completely forced synchronisation doesn't do what it's supposed to do.

This only happens on my P4. All other devices that use Gpodder for synching are working fine.

I already deleted AntennaPod from the P4, deleted its authorisation in Nextcloud and reinstalled it from scratch, but that did not solve the issue either. In contrary: after the first synching very old podcasts appeared, that I unsubscribed some time ago.

Has anyone noticed such a behaviour on any device?

My idea what to try next is to completely delete the Pixel 4 and everything related to it from GPodder's memory, that is: wipe it from Nextcloud's MySQL database, so that next time I reinstall AntennaPod on that phone, Gpodder will really see a completely new device, without excavate any old data.

This is where I need some help: could anyone tell my how to do this, please? Many thanks in advance!