Im kind of ambivalent on this.
On one hand, ~medieval times, which are usually the general era and technology level the average fantasy setting plays in, have no concept of disability and people who have one are usually ostracized and/or begging in the streets. Blindness may be on the more tolerated side of things, but deformities or developmental abnormalities are definitely not accepted. Also, if there is magic why wouldn’t they use it to cure it?
On the other hand, it’s a fantasy roleplay setting and the primary function is to be fun. So if everyone agrees it shouldn’t be a problem to have a scenario with it, more power to you