So you mean nothing whatsoever has changed on your computer in all that time?
(No new installations, OS, videocard, drivers,
automatic updates ...etc?)
I for sure don't have all the specs of your PC.
(In fact you provided no info at all concerning your PC nor BS.Player-version used).
So, as earlier indicated, please just try different rendering modes.
It usually is the fasted method to get matters fixed. Really, believe me, it is!
If you have no intention to try anything suggested, don't ask for help.
P.S.
Apart from rendering mode, another setting which might be of influence is the setting of "Convert captured images in software"
(YV12 and/or YUY2) under
(Rightclick >) Options > Preferences > Frame and thumbnail
capture