Not sure I've seen on PP but it is an old question, going back centuries over all sorts of art. And there is a wider question can some who has done bad things in one sphere, do good things in another? Can someone who has done evil ever be redeemed ?
I don't know much about Dahl. I know he was in the RAF during WWII so fought against the Nazis. Not sure if we'd prefer "Hated Nazis but didn't like Jews either" or "had lots of Jewish friends but was soft on Fascism". Charlie and the Chocolate Factory and Charlie and the great glass elevator were two of my favourite books as a kid, Matilda was my daughter's favourite. If he had some nasty views they didn't come through in his writing, and the things that do come through I think are things I'm quite happy for my kids to pick up. Enid Blyton seems to have been cancelled in a lot of places (some of her stuff really belongs in the another century), but who was the first gender non-binary person people of my age came across ? George in the Famous Five :-) One set of people want to cancel JK Rowling for her views (while another set want to celebrate her for the very same views), does it change whether the Harry Potter books are good or bad?
There have been artists who we pretty repugnant people - Eric Gill's name often comes up in this context, painting and the visual arts have a long trail of dreadful people. Stephen Fry I remember saying Wagner was a "guilty pleasure" because Hitler liked the same music... Wagner had some strange ideas but that's over doing it a bit. I don't like some musicians and actors who are bores about political issues, but primarily because they're bores.
According to Wikipedia Dahl considered himself to be anti Israel rather than anti Jewish (and recent months that doesn't seem to be freakish position) and made some observations which today might not be good to say but when they uttered were not controversial. If you dig deeply enough into anyone interesting who's been dead for a while you'll find something you don't like, so I'm all for celebrating his books, and letting his views go to the grave with him.