Vandami Bhante
Sorry, I am just seeing it now.
Yes, there were special permissions, because I had created the files while using the root (admin) account, they were "owned" by root, and I had forgotten to assign ownership to the account used for FTP.
Now I have searched for all files still owned by root and given ownership to the FTP and web server account, which are these files:
./km/tipitaka/vin/mv/vin.mv.01.05.mp3
./user/johann/gallery/share_merits/watpanna_20220202.mp3
./user/johann/audio/dhammatalk/dogstories_exnovice3.mp3
./user/johann/audio/dhammatalk/morningchanting_nature_vs_dhammika.mp3
./user/johann/audio/dhammatalk/dogstories_exnovice1.mp3
./user/johann/audio/dhammatalk/dogstories_exnovice2.mp3
./user/johann/audio/dhammatalk/decitionbetweensensualityandbecoming.mp3Now in progress uploading all tag-ed files anew, Atma simply deleted them first.
So it was possible to delete files owned by root via the FTP account? Interesting. It seems that is possible because the directory is owned by the normal FTP user. With that, although it cannot overwrite existing files of different "owner", it still can delete everything inside it.
Learning new things every day.