Ssh key not automatically unlocked for use in shell

When I open a terminal on my private laptop and want to connect to a server with ssh, my key is not used, but I’m prompted for the password. With

eval  `ssh-agent
ssh-add

I can unlock my key without problem, and then in this session I can use ssh without entering the password, and the key is used.

On my work laptop, also with Manjaro, the key is automatically unlocked.

When I open a root shell on my private laptop, I see the following error message which seems to be related to my issue:

$ su                                                               ✔ 
Passwort: 
** Message: 21:38:14.443: The control socket is not owned with the same credentials as the user login: /run/user/1000/keyring/control
discover_other_daemon: 0** Message: 21:38:14.444: couldn't connect to dbus session bus: Fehler beim Senden der Anmeldedaten: Fehler beim Senden der Nachricht: Datenübergabe unterbrochen (broken pipe)
** Message: 21:38:14.444: The gnome-keyring control directory is not owned with the same credentials as the user login: /run/user/1000/keyring

Some time ago I re-installed Manjaro after major problems with the system, and I used a backup of my home directory. Maybe a config file from the old system causes a problem? But which one?

Do you have an idea how I can fix this?