Since the update to WordPress 6.0, I can no longer make color settings. The selection menu disappears almost all the way to the left, so that selection is no longer possible. With generateblocks, certain functions (layout, header …) are no longer displayed at all since the update. I have already written something about this in the appropriate forum. Maybe this is related? No idea.
I have the same issue. I only have three plugins installed: GP Premium, Gutenberg, and GenerateBlocks. I disabled Gutenberg and that fixed the issue mentioned by the original poster. When I reactivate the Gutenberg plugin, the problem comes back.