Rated ~800 in standard controls, but 15th in a variant

Can this be considered a type of "sandbagging" in some cases?

I'm writing this here because it's not meant to report someone or just ask the question. I think it's worth some discussion.

I played the following game terribly, partially because I thought my opponent was very much weaker, considering their ratings shown. But suddenly their play boggles my mind, I have no chance. So I go check their games and see they are above 2100 in horde, and other decent/average ratings in variants, only 800-ish in every standard form, which are shown first.

pt.lichess.org/eZN4Q0h1

I felt very deceived and discussed on chat with the player, which wasn't very convincing. They said to be weak in standard chess and connection issues... but only in their standard games do I see nonsensical moves, and most variants aren't that different from standard. Anyway, the point is...

Have you seen such a thing? If done intentionally, is it even useful for deception other than this coincidence that they were playing one of their first chess960 games against me? Have users been notified or restricted/banned before for doing this? And how to be sure whether it's on purpose by the user?

If you believe a player is cheating you should not come to the forum and make a vague accusation. If you think someone might be sandbagging, boosting, or otherwise not playing fairly you should report them using the link from their profile.

this player :romsou too is a cheat why he have a high elo in antichess and a low elo in standar chess¿

You played bad and he won easy .
Some players are good in some variants and bad in standard chess . I dont believe that he used a engine in this game

I recently played against someone on a different site who moved half a year ago.

His Bullet rating dropped around 600 points over the course of three weeks until he gave up and switched to classic/costum.

So as soon as he gets a better connection he will "sandbag" like in your example.

What I mean to say is, it'd be much more difficult to get bad on purpose and it's way too easy to have it happen by accident.

I really focus on the matter of (supposedly intentional) behaviour of faking oneself's strenght by keeping very low ratings on standard time controls. Then you start a variant game with such player, take a look at their ratings and take wrong conclusions that influence your play.

@Langour The second line of my post explains that. I'm not gonna report people for something that I don't even know if can be considered cheating. That doubt is partially why I created the discussion. Here we can discuss the deceitful behaviour. Maybe I could have made a question, but I wasn't sure and posted on general discussion.

@Psyman2 Yes, it's complicated when the user plays at different connections and has issues with some, which is what my opponent alleged. After all, users must have some freedom of experience in the site. The line of cheating is difficult to draw.

Thanks for responses.

No it can't, and no it isn't.

stop being so uptight, man... chill @Toadofsky