enabling any of the overlays causes text, the tab menu and the text log to go completely grey in spectator mode.

This is usually caused by the Fast Render option in Optifine together with MiniHUD, and I've yet to look into why exactly it happens.

I fixed this yesterday in c5f8f22. So the fix will come into the next builds when I have the time finish the features I want in the next builds and then port all the new code first to 1.13.2 and then to 1.14.4.