Why do you switch on laptop (Windows 10) again after I close it and it is in standby mode?

I often fold e.g. The laptop too because I e.g. Take a 20 minute break and after a few minutes I hear the fan in the laptop because it has started again. Sometimes the laptop then goes off on its own after a short time, sometimes the laptop just stays on until I'm back on the laptop, even when I'm 45 minutes away.

So what can I do to prevent my laptop from turning on again (except shutdown, of course)? Is this any system error? I do not quite understand what it would bring that the laptop simply turns on again by itself.

Look in the Windows Event Viewer. Had problems with virtualbox that woke my PC from energy saving mode every few minutes for no reason

Check your sleep mode settings. If it says "never" everywhere, I would imagine that he doesn't know what to do.

This has something to do with the "energy options". There you can set what should happen when you close or press the power button, after what time the energy-consuming components should deactivate, etc.

right click on the start window and then on "sytem" and then on "energy options" or similar

Ok then what do I do in the event viewer?

When I search for "energy options", "Network operation and energy saving" is displayed. It simply says that the screen turns off after 10 minutes of inactivity and that the PC should never switch from sleep mode to hibernation (alternatively, instead of "never" I can choose between different times such as 5 minutes, 1 hour or 5 hours). What can I do to prevent the laptop from turning on again?

On the left are a few links to the setting options, just search and try it out until you are satisfied.

keep in mind that you have to think about saving energy in battery operation, because it still uses some energy even when it is at rest. In mains operation, you can "forget" about saving energy.

There are many possible causes for the problem and correspondingly many possibly helpful instructions. A quick Google search provides e.g. This one:

https://www.deskmodder.de/wiki/index.php/Windows_10_PC_wacht_immer_wieder_auf_So_kann_man_es_%C3%A4ndern

https://win10-tipps.de/windows-10-wacht-aus-ruhezustand-auf-standby-probleme-loesung/

https://www.windows-10-forum.com/tipps/744.windows-10-pc-wacht-immer-wieder-von-selbst-auf-was-tun

And that the PC should never switch from sleep mode to hibernation

That is exactly the problem.