I've suffered with this problem for literal years and it's driving me bonkers.
Every so often - usually within 3-4 months, but sometimes within only a few weeks - my Application Password on my BitBucket account stops working.
I use the app password exclusively for SourceTree, and what happens is I open up the program, attempt to do a push, and it asks me for my login credentials (which are already saved). I re-enter them, and they fail. So, I have to go and create a new app password. It's the only solution that ever works (and I've learned this the long, hard way after spending hours trying to debug the issue previously). I enter my new app password, and it works again... for anywhere from a few weeks to a few months, then the cycle begins again.
I'm assuming this isn't supposed to happen - I never get any kind of warning, and as mentioned, the timing is completely random. I've had one app password that lasted for 6 months, and another that barely lasted 2 weeks.
Does anyone know why this is happening, or is it just a thing?