Not responding when uploading file

It happens frequently, when I want to upload a file (PDF, JPG, DOCX) over a website (i.e. a curr. vitae in an application form) with MS Edge and the explorer dialog comes up to select the file, the window shows "Not responding" and it can't be shut down.
This is pretty limiting for me.

Sometimes I see some files for a millisecond, but then it freezes.
Same with Google Chrome too.
This problem occurs regardless which file folder, various sites, with or without cookies & no pop-up blocker, no anti-virus.

Edge-Version 135.0.3179.66 (Offizielles Build) (64-Bit)

I tried: Updating Edge, repair and reinstall. No change.

Funny side fact: The upload button here works perfectly.