Why do people keep saying this? Weird =\= surprised or unbelievable. In any context people replace unbelievable with weird it’s because they directly don’t want to tell the other person they don’t believe them. That’s when you get the “I find it weird that…” but that’s not because weird = unbelievable it’s because the person is using “weird” to hide their intent.
Same thing with surprised, you can find something weird and not be surprised. I mean for most people there’s probably things you see every day that you find odd, but aren’t surprised by anymore.
It’s just kind of weird to argue the semantics of what someone meant…