That has been a bug with FB even with Android 11. I have found that if I set it to system default and schedule the light and dark modes on my phone it seems to work more consistently.
As the problem involves a 3rd party app, it would be best to contact the app developer for support. However, if you do experience issues with a Samsung app, please send us an error report with a video recording and we would be able to debug the issue. We apologize for the inconvenience and appreciate your contribution to the beta program.
