Bad experiences from the past are valid reasons to be apprehensive.

Gibt gute Gründe die Sicherheit sorum aufzuziehen: der Manipulant bekommt nicht mit, dass er erwischt werden wird.

My Lemmy instance only owns this account, not secondary accounts on separate websites

But why? Just use a password manager instead of tying your identity to a Lemmy instance which you do not control.

Having SSO is reliant on having a single trusted server which has your password instead of you maintaining it yourself. This is just an unnecessary risk.