Not a bug, a Microsoft 'feature'... yea, I know
Replying quickly, hopefully others who know more/better than I will respond
I haven't upgraded to OBS v27 but I know with OBS v26 and a nVidia GPU I have to use the older Windows capture of Blt??? to keep my cursor hidden. So I won't be surprised if a related change to capture approaches and Microsoft display driver changes are causing a change of behavior which might be unexpected. Have you tried changing your method of capture (be that Display, Game, Window)... my apologies, at some point, I recall someone mentioning a preference order amongst those, but not being a gamer, I didn't commit that info to memory.