Does it work when you extract the bitcoin core tarball to your home folder, run chown with your user and group, and try to run that bitcoind?
I mean, I doubt this will change anything, given that the file is world-executable, but its worth a shot.
Also try checking file output of other files in /usr/bin to make sure that they match with the one you got for bitcoind.
So, I ended up upgrading my Raspberry Pi 4 to a 5 and had to start everything from scratch (installing the OS), and now I can execute those binaries without a problem. For me, what was happening is still unknown. If I have the time, I will try what you suggested and report my findings here.
Thank you for your support nevertheless
![Smiley](https://bitcointalk.org/Smileys/default/smiley.gif)