Is actually something done with my reports?

Yes. As a moderator, I don't directly see the poor sportsmanship reports but when people get reported for poor sportsmanship often enough, they get assigned to a special pool with others of their ilk.

We have often seen them coming into the forum complaining about their assignment.

Did you watch the State of Chess broadcast yesterday? https://www.chess.com/news/view/2024-state-of-chess-august-1

In about 50% of the games I win, the opponent walks away after the position is lost without giving up. Most of them do not disconnect, they stay online but stop playing.This can be rather annoying, so I always report this.But is there actually something done with those reports?

50% is a high proportion. A small minority of my wins do that, but usually in that case it is game abandoned and after two minutes or so the clock runs down. I remember once a character with a pirate as an avatar walked away from a not necessarily lost position and it took nearly 20 minutes for the clock to run down. I guess it was an example of the opponent's piratical approach to chess. Naturally I reported it but it was an extreme case.

Accounts are closed every day

I see accounts closed every day

The vast majority of games are played honestly and the vast majority of cheat reports are unfounded.

Your opponent is probably not being truthful. If you reported and the account wasn't closed after a few days then either

• There's insufficient evidence of cheating 
• There's no evidence of cheating