As someone who plays a shit ton of romhacks and fangames, the ones that get taken down by Nintendo tend to do something really fucking stupid, or have "fans" that do something really stupid like directly tag nintendo in posts as a weird attempt at gloating, or at least won't shut the fuck up about it. "Oh, you made a pretty cool hack of breath of the wild, that's nea- Oh my fucking God, you provided a detailed step by step instruction on how to pirate a current gen nintendo game that still sells like 2+ million a year next to an advertisement for your patreon, what the fuck are you doing?"
Ones that just provide a patch and tell you to find your own rom to patch onto are safe 99% of the time.