Probably a boring answer but I know my grandmother’s credit card information. I live with and help take care of her, so she doesn’t mind sharing it with me. Not like I’m planning to do anything nefarious, but I guess technically it could ruin her financially.
If you’re using bitwarden or keepass then it should be safe. Anything else is asking for trouble.
Self-hosted and entirely under my control, yes. Any other manager that encrypts the store in a way where even when breached it’s not useful, should also be safe…
But truly knowing is best.