League of Legends Client problem with second monitor?

Hi

I bought a second monitor for Blackfriday.
In contrast to my laptop, it has a 4k resolution, while the laptop only has 1080p.

The laptop easily manages 4k at League of Legends over 100fps but as soon as the game is over, the client hangs for several minutes and there's "no feedback" although I can do everything else in time, i.e. Browsing or talking in Discord.
The game runs at 1080p (since I hardly see the difference to 4k ingame and want to protect the laptop from overheating). Otherwise, the monitor runs on 4k, i.e. The monitor switches the resolution when starting the game from 4k to 1080p. Switching takes a few seconds, if any, but the client is always freezed.

However, if I set the monitor to 1080p right from the start and then play normally, there's no such problem. However, I don't want to change the resolution of the monitor every time I play LOL. Especially since it still works normally a few weeks ago and has only recently appeared.

Is there a solution so that the client is no longer freezed?

I don't think there's a solution. But I don't think it could be the monitor or laptop either, just the latest patch. Since the latest patch from Riot I also have the "no feedback" problem after Games. No idea what Riot has screwed up again this time.