Supervision flickering is a known issue. It’s not only when recording it can happen at any time. However, in the meantime there’s a solution / workaround to the flickering here: Graphic Glitches in Cubase 13 on Windows - #101 by manassas77
As suggested by Johnny above, I’d suggest deleting [temporarily moving] your preferences and starting afresh with factory settings. This can solve a lot of strange issues.