I've also encountered this issue. Currently, I'm using the Quest 2 with system version 68, and reinstalling the software doesn't seem to help. However, the Meta browser and other video playback software are functioning without any problems. Visually, I can't tell that the video is playing in slow motion, but the audio sounds like it's slowed down, making it difficult to understand what's being said.
Another issue I've encountered is that browsers using the Google kernel for sideloading (such as Edge, Brave, and Chrome) produce a kind of crackling noise reminiscent of electrical current, whereas browsers using the Firefox kernel do not exhibit this problem.