I can’t believe XXXBios is not an option when adding links for performers on StashDB.
XXXBios has a collection of biographical information on quite a few of performers that is most factual and comprehensive you can find on the net.
e.g. Lena Anderson Biography on XXXBios
Validating regex (Is this what it’s called here?) could be:
^(?:https:\/\/)?xxxbios\.com\/[^/]+-biography\/$