Yes and also other (non-media) content since the folder is used by all download clients.
Progress! I have created a completely new library and cannot reproduce the issue there, I don’t even have to create an empty directory with the same name, if a folder with media content is deleted it is just removed seconds later.
The current folder houses about 10.000 files, which is more than 8192, I have read somewhere that there is a limitation - could this cause the issue?
Thanks again for your support and I wish You and the whole team a happy new year!