Cheating is not only done with max level stockfish on all the time. Most of the cheating is what I'm calling casual cheating: looking up strings mid game, having lower level stockfish on all the time, or using high level fish accompanied by your own moves.

I can say for fact on both lichess and chess.com, at the intermediate bracket nearly 60% of matches I'm playing have extremely questionable games that have all of the following qualities (I play 10 0)

1) Literally never has a single turn more than 20 seconds. Usually is never more than 10.

2) Has much higher CPL/Accuracy than is appropriate for the intermediate (1000-1500) bracket (usually 80% or 50 or less CPL every game)]

3) Never makes a blunder (not unheard of on its own at all, but when it's accompanied by playing very fast in rapid rating or just overall suspicious play it just reinforces it)

4) Is at their peak or near their peak, with a sudden surge in rating not too long ago

5) account no more than 3 months old

Any one of these things on their own isn't enough cause for concern, but we'll over 60% of players I'm playing in the intermediate bracket fit most if not all of these conditions.

They always perform these inhuman moves of retreating a knight 4 moves in a row to move it to the opposite side of the board and eventually that becomes a major pivot in the game. It becomes so obvious catching cheaters to the point where I'll check their account after reporting them a month later, they will still be unmanned and have a record of 120W 15L in that time period.

It's actually shameful how obvious they get but how little they do about it.