I've been having a similar issue (I'm using a Pixel 8). This has persisted for me since my first upgrade into an Android 15-based build on the Stable channel (I think that might've been build 2024101700? I'm not sure. I can't find where in GOS' release notes whether a specific build was actually released to Stable). Here are my reproduction steps.
- Be on a pre-Android 15 build of GOS
- Create secondary user profile.
- Disable fingerprint-based unlocking for all user profiles (Primary and Secondary). Use only alphanumeric passwords (no PINs) for all profiles (again, both Primary and Secondary)
- Upgrade to any Android 15-based build of GOS
- Switch from Primary user to any of your Secondary users and try to unlock via password.
- System will tell you that you have a wrong password regardless of how careful you typed.
- (Workaround) Tap your Pixel's power button (the button on the side of your Pixel that isn't a volume button) once to put it to sleep. Tap it again moments later to wake it back up. Now try to unlock via password.
- The phone unlocks normally (assuming you actually typed your password and made no typos, of course).
Diagnostic info:
Phone: Pixel 8
Android Version: 15
Current Build: 2024110700
Current Channel: Beta (Switched to Beta in the hope I'll get an update that fixes this bug a bit sooner)
Edit: Because I saw some people asking OP this, my keyboard is using the default for the en-US region (American QWERTY layout, in other words). I am using the default keyboard app provided with GOS.