(Having said that I need to admit I don't know of any specific sfw relays. But that's probably because I never worried about it. Im sure there must be some/will be some soon)
You can prevent that by tailoring your write relays just like nostr:npub1dy7zsvk7jwd547xvmpptzlc9muhd64g7txvf60zwlxjyj4aj78as6hljz5 said 😉
Discussion
Still I use the ones by "default" anyone joining use those, and it can cause a bad first impression. I am probably stepping into unpopular opinion here but it is an honest impression that may represent others too. So I had to speak my mind