Suspected cheaters are across the hall from convicted cheaters but up-stairs from Scams, Scoundrels, and suckers.
Another cheater thread
Without knowing which game you are referring to... or at least the date and whether or not it was online or live it's difficult to (so I can look through all of those ones) it's difficult to see what might have caused any suspicion on your part.
I've assumed that the player in question won a game against you... but you don't appear to have lost a game to anyone significantly lower in rating than you recently. And even if you had, losses to lower rated players are just somethin that happens sometimes.

How do you report a suspected cheater?
Submit a form to the same place you report other things: https://support.chess.com/customer/portal/emails/new

just play your game.when finished have it analyzed by chess.com computer. if cheating is envolved it will show up.loss an opponent in one of my tournaments that way.

hahahahahahahahahah touche!
Ronald, why is your surname not pronounced "coat"? It's like "coatie" right?

Yes buddy, its Canadian French. Grammar school wasn't fun. It was Cotex, or Cooties
Hehehehehehhe

If someone cheating at correspondense it may take few months to remove him,for live chess it takes few hours
How do you report a suspected cheater? I've tried to find out on the support section and can't find the imformation there. I send an email to a staff member and it promptly bounced.
I don't see cheaters lurking behind trees and bushes, in fact this is the first time I've been convinced a guy is cheating.