The best solution is to avoid resetting the Note10+ for now. do not use Google Find Hub or Samsung Find to erase it, and do not keep guessing the PIN, unless the new PIN had been set in the last 3 days. First, from another phone/PC, check Google Phot...
If all passwords are changed and unique, the warning should eventually disappear in a few days. review logged-in devices and active sessions, remove any unknown apps with account access.