Personal access tokens keep disappearing

My personal access tokens keep disappearing (even when they should “never” expire). When this happens, it breaks all of our automated and is a huge inconvenience. Any insights into why this might be happening?

Did you check exp claim in your token?
If it’s not there it means the token should never expire.
Another possibility is that the user was edited.
Even if there is no exp claim we invalidate user tokens on user object modifications (because, for example, role can change).