Actually, new stuff in Skyblock is being detected as I've heard, ghost blocks (created not legitimately) are bannable because you're sending block-breaking packets and game masters can see that.
Along with auto-solvers (eg. auto terminals etc), but in this case, for other gamemodes it would be chest stealer, is also being detected (specifically on spectate).
In addition with that, (for Skyblock) if you are reported, Admins will eventually check or spectate you, since all reports are still manually reviewed by Admins (gamemodes that are unrelated to Skyblock, Admins can use Atlas to prioritize people who others deemed were cheating and push them up in chronological order)
In this case, all sorts of players would get banned, which doesn't exclude high-level players, though, it could be coincidental.