The issue is that they are cataloging both the actor’s page on the site with their current name as well as the credited names from movies.
For example, if you look up the Matrix, it says Lana and Lily Wachowski, but also notes how they are listed in the credits with their deadnames. But you look up Sense8 and there is no mention of other names.
I get why they do it. Actors often go by different names for various reasons. And for a website of trivial knowledge that nice to have. But for trans people its an issue of privacy and at the very least safety.