After updating Firefox for Android, my phone started rebooting after downloading any file. This makes it very difficult to use the browser and I had to use Chrome temporarily. The Crashes tab in About Firefox is empty. I tried to collect a logcat and uploaded it to Google Drive (maybe this will help somehow.): https://drive.google.com/file/d/1kmdS5rTH3r0u09KLxeUDeY5U8r5xiEK1/view?usp=sharing. I hope this information is helpful in solving the problem.