#1
It is impossible to tell.
Maybe your opponent analysed for 24 hours and came up with a brilliant move.
It is a reason not to play daily.
The International Correspondence Chess Federation now allows engine use, as it could not patrol a prohibition.
Cheating in daily matches?

Playing almost exclusively daily, the only way to tell for me had to be the notification Chess.com gives you later, giving you bonus points, telling that an opponent was cheating afterward. Else, I never really assume a player cheat, I’m not a good player, so even looking at a pretty good analytics, I just suppose he simply is one.
Is it really a daily games specific issue, tho ? Even in real time games, engines seems to be pretty easy to use everywhere and anyhow now, there is even web browser addons for that…
Also, in daily, more time means more ways to look for a good move anyway, for example, does googling « pawn and rook final » in another window in considered cheating ? I mean, Chess.com itself gives us many features to be better in daily, like openings books or analytics.
#3
"Is it really a daily games issue tho ?"
++ Yes. In daily games there is no information on the time per move spent.
It may be 24 h, it may be 24 s. There are also not enough games to base statistics on.
Also if I play 100 daily games and spend 24 s on each move, I may get a low rating.
If I then decide to play 1 game only and analyse 12 h, then I play much much stronger.
"Even in real time games, engines seems to be pretty easy to use everywhere and anyhow now"
++ Yes, but cheaters get caught eventually.
Top grandmasters prefer 1|0 bullet to avoid cheating.

When you play Correspondence, you’re accepting that you’ll lose to some cheaters (who’ll never get caught).

I see, yeah indeed, I understand how cheating can be more obvious in real time game.
Can’t there be bots to play for you even in bullet ?! ^^ Or is it way too obvious maybe. But then, what if it really is a good player ! lol
One thing’s for sure, indeed, cheaters ruins the fun for everyone everywhere anyway. Not only chess. Another addon could be made, that works at first but then slowly degrade, or blacklist the player, as they did with some online games ^^ Wasn’t it told for a time that Lichess was detecting cheaters better ? Or maybe just because they’re less mainstream.
Considering your daily rating, I would not be too worried.
I have been able to beat people with a similiar rating pretty consistently.
One opponent may have been cheating since I got rating points refunded, but other than that it does not seem to be a big issue at our rating level.
Just analyse, take your time, look at the position, make notes, look at it later with fresh eyes and check if your notes still seem to make sense and only then play your move. Use books, use the opening database, watch youtube videos on the opening you are playing. These resources are allowed in daily.
Just do not use an engine or ask what move to make from another person. These are the things that are not allowed in daily.
I sincerely think I have faced more cheaters in rapid and blitz since I have gotten more rating points back in those time controls.
So, NO, I don't think it is any more of an issue in daily than it is in the other formats.
And I am not accusing anyone of anything here, I just know some cheating happens since I have been funded some points back.

https://support.chess.com/article/648-what-do-i-need-to-know-about-fair-play-on-chess-com
Discussions of cheating, potential cheating, or cheat detection are not allowed in the general forums.
If you suspect an opponent of using disallowed resources, you should report them.
https://support.chess.com/article/209-how-do-i-report-someone
If you would like to discuss, join the following club: https://www.chess.com/club/cheating-forum
This is impossible to accurately measure, so I am asking for your general impression and personal experience, really. I only play daily tournaments, and I do get the impression that there are players who cheat, but I am hoping that these are rare events. Your thoughts?