Hi, I'm still new to reporting bugs so I don't want to mess up an end up being more trouble.
The issue is that, for some reason the viewport is stuck with the previous image displayed. Even after the splash screen or any of the other tabs it still displays whatever was on the viewport area.
However, it does show correctly for a milisecond once I click the close window.
Happens with the PPA version and the running from source version, this last one works fine if I use the --noshaders option from the terminal, which is a bit tedious.
I'm using Ubuntu 20.04 LTS. Screenshot in case I wasn't clear.