Why does it say Warning ________ losing games on purpose will result in a temporary ban

It was 0+1. Though I won, it gave a warning or losing games on purpose for my opponent. Can you tell me why?

They might think you're farming rating points and don't want to have that happen. That's what has happened to me

Not to explain how the system works and give it away but yah the sandbagging detection is not nearly as good as the computer assistance automated detection system. Just as computer cheating is a problem here and on every online chess server so is rating point farming which is alot harder to catch.

I think it is not hard to understand why allowing mate in 2 with Ke7 is not seen as normal play, but an attempt to lose.

What is more nuanced, is that this would lead to people having the wrong rating, especially if done regularly. And rating manipulation, in either direction, disturbs the system.
Which in turn should be bannable if taken too far.

Any game that last less than five moves will gat a warning. Lichess discriminates against the Bongcloud.