Since it runs in your browser it depends on how fast your computer / device is.
I've beaten level 9 without take backs on my computer, but it's annoying. It will play like an idiot 1 or 2 moves to give you a better position, then play like a 2200-2300 trying to stop you from winning.
And sometimes you get lucky and it plays a terrible opening.
If you want to beat a level you haven't yet, I definitely recommend restarting after 10 moves if you're not already up material and trying again
But level 10 seems to play at full strength the whole game. If there's only 100 or 200 points between all the other levels, from 9 to 10 is more like 600 rating points.
Interesting. So the skill level may vary if your computer is slower?
And level 10 plays exactly like it sounds like it should (I'm guessing full stockfish?). Nice.
(I mean this computer: https://www.chess.com/play/computer, not any other ones)
I just want a point of reference. I've been able to beat level 5 (without hints, evaluation, takebacks, all that), but level 6 stumps me hard. What's the highest level you've beaten?
P.S. Is there an estimated ELO rating for each of the 10 computer levels?