BOINC doesn't work from repositories

I just (re)installed boinc, but it can’t start the client. When starting the client manually,it complains about not being able to read gui_rpc_auth.cfg

Running the flatpak version works without a problem.

Anyone who knows what might be the problem here?

Would you be able to provide the version of the BOINC client and the distribution you are using?
And where is the gui_rpc_auth.cfg file typically located with and without Flatpak?

So, the version in the repositories is 7.18.1 (pre-release), whereas the flatpak version 7.22.1.

I think that both version try to acces the same gui_rpc_auth.cfg file, as when I start the repository version alone, it complains about not being able to start the client. But when I start the flatpak version first and then the repository version, it says it can’t acces the gui_rpc_auth.cfg file (probably because it already has been opened and locked by the flatpak version).

The working directory of the flatpak version is ~HOME/.var/app/edu.berkeley.BOINC/
the repository version is under ~HOME/.local/share/boincmgr.

Oh and I had two gui_rpc_auth, one in the flatpak folder, one in my home folder. But even deleting this one didn’t change anything.
And now the repository version complains about not being able to read the gui_rpc_auth.cfg file even after closing the flatpak version, probably because the client is still running.