@Akero well, long and short of it is that if anything happens to corrupt OSCrypt. It uses your keychain to handle passwords. Often when people report it’s “deleted” as you are, they are actually still in the User Data folder but can’t be fetched due to the loss of the encryption key.
It’s been several years now and nobody has been able to pinpoint exactly what’s going on. They only are able to present a basic concept of something that might cause it. And what’s trickier is nobody can replicate it, nor are there any types of diagnostic logs to be able to run. It just seems to randomly occur to a very small subset of people.
You can also kind of see what I mean about it being ongoing for a while in below, as well as see the types of things they have said: