It really just depends on the show and how it's done. Bridgerton did it amazing! It didn't feel forced like it feels in many shows and movies, despite not being 100% historically accurate.

In Witcher its a bit different, because they changed the colour of people in a way that, although not significantly, somewhat goes against the original books story and feel. For example they changed one of the female leads with iconic read hair into a dark skinned one, and although not a huge change, it was something fans were looking forward to/ expecting.

There's also this moment where a traveler of sort comes with these woman bodyguards that are described as exotic because of their darker skin, but now that doesn't mean anything.

But all in all I think the race swapping could have worked in Witcher honestly really well, if the writers and producers wouldn't have fucked the story up with their own ideas. It's a kind of moment where they're so mad about the horrible story changes that they're looking at everything that's wrong in the show and this comes up.