@nutmegcat: I'm sorry to hear that this issue has returned. If you found that wiping the cache partition resolved the problem initially, are you able to pinpoint any actions that you have performed in the interim that might have resulted in the Samsung Pass/Google Password Manager details not populating as expected?
In the meantime, please try heading to Settings > General management > Passwords, passkeys, and autofill > Preferred service, and make sure that your preferred option is selected from here. You may also wish to try setting up an alternative service to see if you experience improved stability. Let me know how you get on.
