Incorrect password errors on oauth2 api, not web

Hello! We've integrated a system with the V1 api, and use the https://auth.roserocket.com/oauth2/token endpoint with password grant to retrieve our bearer tokens. The issue we're facing is that occasionally we will begin to receive 'incorrect password' responses, when the password has not changed for the user. Logging into the web portal with the same 'incorrect' password works, and if we 'reset' the password for the user to the same stored value we have (and just used to log into the web), the error response goes away.

Unfortunately so far, we haven't been able to see any direct pattern in when/why the errors start.

Is there a known issue/process happening here, and if so is there a specific way we can avoid having to manually 'reset' these passwords in the future?

Thank you!