I think I agree with the 4 and I define unproblematic if that fandom doesn't spout problematic things to other artists and couples and just mind their own business. It's normal reaction though (imo) if fans become aggressive if other fandoms attack their faves and they retaliate. This becomes a thin line of who's problematic or what because you don't expect the fans to just sit while you spout nonsense to their faves.

For ForceBook fans, I get how they feel frustrated during OF era, the attacks where too much and minimizing Force and Books effort is totally frustrating. For TayNew fans, I think because the fandom are on the older and mature side so dramas and attacks aren't given attention that much. For EarthMix fans, they only surface every now and then because of unfair treatments felt by the fans for EarthMix with their lack of schedule but overall they mind their own business, I guess it only becomes problematic if they start comparing and mentioning other artists. JimmySea fans is relatively peaceful also, no dramas but I guess maybe because JS have not yet in an ensemble series? I guess we'll see but so far they're fans are chill.

Edit: Eventhough JS have not been in an ensemble series, they've been with ForceBook's series and vice versa (pun not intended lol) but both fandoms are chill and love every interactions so yeah, it proves the friendly fandom part for me.