Catalina update bad experience

I would like to point it out. I updated my Mac with Mojave to Catalina.

I didn't expect a so problematic update.

I did Mac OS several updates in the last years and this one was horrible.

I had major issues with graphic card I think, that's Apple hardware. I own a Mac Mini 2018.

I think that a non experienced user like me should have gone to an Apple center to get rid of the OS not starting at all.

Really bad experience since the download and install.

Now the OS is running with some - silly - annoying issues like the hour completely wrong according to my location.