Weird one…
When I first installed plex app on my Macbook it asked if I wanted to change the logo, I tried but for some reason it wouldn’t let me select any.
I now don’t see any options inside the app for this setting and re-installing the app it no longer gives me this option.
Does anyone know where I can do this?
I don’t think any of the desktop apps has ever supported changing the app icons. The mobile version has such a feature – hence my suspicion you might have had that installed at some point on your desktop (as you can install mobile apps on the m1/m2 macOS).