Sneasel-Hisui:
ban: way too powerful and fast for the current meta, switch-ins are limited to Mareanie, phys def crocalor, and physically bulky ghosts. all suffer from Switcheroo, with mare being ruined by Taunt, Croc from hazards damage, and ghosts with night slash. Inner Focus prevents even Qwilfish-H from checking it with Intimidate, and now resisting Stealth Rock combined with either making the opponent guess between SD and Band makes it absurdly hard to answer.  

Qwilfish-Hisui:
ban: Not as problematic as Sneasel-Hisui but I honestly think it's way too effective and consistent for its set variety. Defensive Spikes sets have great matchups against numerous Spikes and Stealth Rock setters thanks to Toxic/TSpikes like Glimmet, Toedscool, and Dunsparce with Toxic, and Taunt shuts down defensive mons like Mareanie and Croc. Offensive sets are very good at cleaning through weakened builds once Tink has been removed, which is quite often considering how Tink is tasked with checking other offensive mons throughout a game. It even gets useful moves like Aqua Jet and the aforementioned Taunt to further solidify its matchups. 

Sliggoo-Hisui:
Do not ban. While surprisingly annoying to deal with, esp. when compared to its regular form, Hisuian Sliggoo relies a lot on not facing Mareanie and/or Crocalor on its builds. It fails to pose a threat early-game and hates dealing with Knock Off and Trick, both of which has seen a rise in use. Most importantly, hazards are very popular and can easily get chipped down when trying to set up or check threats, making it harder than one would expect to perform. While very bulky and more threatening as a Curse sweeper compared to its regular form, I don't think it's oppressive enough to get banned.