Big Sur 11.4 update has lead to issues with all video playback on my MacBook

The Big Sur 11.4 update has lead to issues with all video playback on my MacBook. Has anyone else experienced this problem? It doesn't matter whether I try to play back videos in Quicktime, VLC, Spotlight or online (whether it be Netflix, YouTube or Vimeo) - playback doesn't start and the screen freezes, because the computer is "thinking". If I restart the computer, maybe I can get a single playback to start, but it will stop after a while, and if I pause, it also won't restart playback when I unpause.