Hi Rob, well I was thinking about that because that behaviour is unussual (at least for me). In general you are always safer to go with LTS versions and upgrade to next version at least year after it was released or even when following LTS version is released. I would stay on 20.04, which work really well for me.
I’ve tried 22.04 on one older PC (which is still good for multimedia) and ended up reinstalling 20.04 as the newer version didn’t really bring anything better to it, but the performance degraded significantly. Also some extensions were not updated yet, so even user experience degraded.
Edit: or hold on, seems you are not the only one with this problem: Certificate verification failed The repository does not have a Release file