For anyone who's read the Drizzt novels, it's pretty well established that the people of the Forgotten Realms freak out when they see someone who looks like a monster (see the reactions to Drizzt). It's quite jarring that Tieflings are seen as anything but KOS monsters. Based on those books, you'd never even start a conversation with one. You'd just shoot the Tiefling on sight from long range (or flee).
The books are informed by the D&D lore, but they aren't canon.
It just seems like a strange contradiction if you came to the FR via the novels.
Totally agree that any PC race will be normalized. But I do think it at least warrants an explanation when BG3 sets up red-horned devils as actual devils from hell. A few lines of dialogue from Lae'zel when you first encounter the Tieflings at her cage would work. (Or she could say something in the Prologue if the PC is a Tiefling) It's a fairly easy problem to address and it makes the story feel more realistic instead of hand-waving a glaring plot hole.
