/run/user/1000: What to do with it?

My main question is about /run/user/1000:

• Should I avoid touching it?
• Could I delete it?
• Is there something wrong with it?

Background: I'm fairly new to Linux and just getting used to it.

I use fsearch to quickly find files (because my filenaming convention helps me to get nearly everything in mere seconds). Yesterday I decided to let it index from root and lower instead of just my home folder.

Then I got a lot of duplicate files. For example in subfolders relating to my mp3 player I even discovered my whole NextCloud 'drive' is there again: /run/user/1000/doc/by-app/org.strawberrymusicplayer.strawberry/51b78f5c/N

Searching: Looking for answers I read these, but couldnt make sense of it.

• https://unix.stackexchange.com/questions/162900/what-is-this-folder-run-user-1000
• https://forums.linuxmint.com/viewtopic.php?t=412850 So if its a bug with flatpaks I'm inclined to delete a certain db at ~/.local/share/flatpak/db

Puzzled:

• Is this folder some RAM drive so my disk doesnt show anything strange? Because this folder doesnt even show up at the root level.
• Are these even real? Because the size of it (aprox 370 GB) is even bigger then my disksize (screenshot).

Any tips about course of (in)action appreciated.