So you worked for twelve years on that code base and you still don’t know how to estimate a bug fix? There seem to be other problems then.

And you are right, I don’t know anything about that code base, certainly not enough to know if estimates should be easy or not. But the fact that they aren’t is a sign of problems either way.

And I stand by my point that your boss’ question is reasonable, and the team should do some introspection to learn why such a fair question cannot be easily answered