plugin works great and seems to be functioning just fine in 1.17 as well

as a bonus no mobs target you if you become in range, WHILE already hidden, of them untill you bump them

becoming hidden while being targeted by a mob has no effect and you will still be attacked

players can not be seen unless wearing armor/holding items

players can noticablely bump into invisible players (hidden vs non hidden & hidden vs hidden)

hidden players are completely hidden in the world (not chat or tab) meaning there are no visible tells such as particle effects, name tag or shadow

additionally if you enable the toggle sneak in accessibility you can remain crouched while in inventory or chat

suggestion:
a way to turn the sneaking ability probs a command