This is about the updated beta version. First of all, I wasn't sure this part warranted an entire question: the app seems to crash for no reason. It is not in reaction to anything overt that I do. I put the phone down with the app open, do something else for a second, then glance back to see the app has crashed. This happens fairly frequently. It also crashes when opening an external link.
The main bug: while I was typing an answer, I needed to do some calculations. First I changed some numbers in my answer without submitting. Then I went to my home screen, opened a calculator app, did the calculation. Afterwards I went back to the stack exchange app to put the number in and found that my changes had been undone. I think this also happens when the screen rotates.