chess.com doesn't want us discussing cheating in the public forums; it just brings too many trolls. Besides, 90% accuracy isn't that strange at all; this is even for someone rated 400 because there's many reasons someone may get an inflated accuracy rating:
Covering up cheating issues!

This happens quite commonly at lower levels too
And regardless accuracy is one of the worst ways tp tell if someone is cheating

How to report someone on chess.com https://support.chess.com/article/209-how-do-i-report-someone https://www.chess.com/forum/view/general/how-to-contact-support-1
It is against chess.com tos to discuss cheating in the public forums, so please keep all discussions around cheating in this club where it is allowed https://www.chess.com/club/cheating-forum
It's disgusting and disgusting. Someone with a 400 Elo is playing with over 90% accuracy over and over again. Chess.com is a disgrace to the chess world and you would sell your honor for money.