I had this issue, it was super annoying. I uninstalled and reinstalled with the latest update and everything worked great again and has been doing so for well over a year. I went down that rabbit hole of trying to update the spoofing settings per fuckyouspez threads and none of those recommendations ever worked for me. Hope this helps!
Settings > Miscellaneous > Spoof video streams > Default client > VisionOS
Also make sure to clear app cache from time to time
Tried that, worked for a day or so and then it went back to buffering.
I had this issue, it was super annoying. I uninstalled and reinstalled with the latest update and everything worked great again and has been doing so for well over a year. I went down that rabbit hole of trying to update the spoofing settings per fuckyouspez threads and none of those recommendations ever worked for me. Hope this helps!