So Tieflings and Aasimar can grow wings now. My question is whether this would actually be a benefit for a character playing in Descent into Avernus, or if the combat areas would make it more of a pain in the butt.
While I can't comment on the adventure specifically, flight is usually a pretty useful tool. As a side, tieflings and Aasimar had the ability to get wings since at least 3e if I remember correctly.