Yes, 1600 self declared non-citizens. Nowhere was it said that they were "illegal" though. They could have been but may not have been.
The Supreme Court issued a stay and allowed it. There was a very good breakdown as to the arguments for it. I'll see if I can find it.
In a significant decision, the U.S. Supreme Court on Wednesday granted a temporary stay in the ongoing legal dispute over Gov. Glenn Youngkin’s executive order that resulted in the removal of over 6,000 Virginians from the state’s voter rolls. The stay pauses a lower court’s ruling that would...
virginiamercury.com
This was a pretty good breakdown as to the arguments supporting why the 90 day rule didn't apply.
Virginia took its case to SCOTUS and marshaled three strong arguments for why its efforts to remove noncitizens from the rolls were lawful.
thefederalist.com