OpenSUSE-release 20250502 apparently included Gramps 6.0.1. However, after starting Gramps again after the update the Gramps ‘Help > About’ function still shows the old version 5.2.4. YaST Software management shows version 6.0.1 is installed.
So which is the actual operational version on my system? Where is the error?
Which package version is installed can be checked with zypper se -si gramps.
Make sure that you don’t have installed Gramps via zypper AND flatpak (there wase a recent post from another user whith a similar issue). And finally check your home directory, search for the Gramps config files and remove/rename them.
How far do I have to go with the renaming? There is one gramps52 directory under .config and several in .local/share all of which I have renamed. But Gramps still opens showing version 5.2,4 as if nothing happened !
You did not show zypper se -si gramps as was suggested and you did report that you checked on a double installation (openSUSE OSS and Flatpak).
People like to hear the answer to all their suggestions, else they will loose interest in your problem.
Sorry… 
~> zypper se -si gramps
Loading repository data...
Reading installed packages...
S | Name | Type | Version | Arch | Repository
---+-------------+---------+-----------+--------+----------------------
i+ | gramps | package | 6.0.1-1.1 | noarch | Main Repository (OSS)
i | gramps-lang | package | 6.0.1-1.1 | noarch | Main Repository (OSS)
…AND I had flatpak installed (mistakenly expected to see it among the repos). . Have now deinstalled it
…and now it ‘fails to launch Gramps’
What is the terminal output of
/usr/bin/gramps
Gramps starts with version 6.0.1 
…but now I need to link that with the Gramps desktop icon, because that persistently fails…
…but how?
Gramps 6.0.1 opens from Nautilus, by choosing a .gramps file (i.e. a backup tree) and selcting ‘Open with Gramps’. However, the desktop gramps icon persistently fails.
I assume you can edit the menu entry/ desktop icon to point to the correct place (right click on the it? at least that is how it works in KDE).
Or create the icon anew from the menu (or is that not the way these are created, I never use desktop icons, thus I am not sure).
I assume that by installing it twice, the last one is connected to the menu entry. Force installing the one you want to use now may set the correct value in the menu entry.
Problem solved.
After deleting flatpak, the Gramps desktop icon continued to retain the link to Gramps 5.2.4, although listing (under ‘App Details’) 6.0.1 from Tumblweed as alternative. Selecting version 6.0.1 under App Details loads that version but continues to prefer the flathub version on renewed gramps start from the icon. The flathub version option is removed after system restart.
OK. And for the future better keep trace (e.g. make notes) about what you are installing.