When I launch Joplin, I just get an empty window. I can see the menu bar (File, Edit, View, etc.), but that's it. It was working fine until recently. Did a recent update break it? The terminal client is working fine.
I'm running Joplin 2.12.19 on Linux Mint. The desktop displays everything normal. I never saw the problem you are reporting, but I don't know when I had 2.12.18 or if that version might have been skipped by my version of Linux.
Experiencing this myself. NixOS (Wayland+GNOME) here. Full log of starting joplin-desktop (I waited some time and moved my mouse since there was some grey flicker - I think the log is very repetitive):