I second this request as I am also running 2022.05.02 on Proxmox from the ISO appliance, using just the mail function as the other parts are not useful to my user base. My IT background is in Windows/Exchange so still on a steep learning curve with linux and this forum. I have already spent several hours attempting this upgrade (see details of what I have tried/found below for those who wish to read it). I thank the many posters on the forum for the time and effort they put in to help the less knowledgeable of us trying to get this all working for our user bases.
I have cloned the my current live VM (2022.05.02) and run 'Zypper Ref' and 'Zypper Up' on the clone and all seemed to run through OK. The rebooted VM showed no unexpected errors in the logs, but the Grub boot screen still showed 2022.05.02 not the new version as I expected. Digging around the forum posts and suggested updating the /usr/lib/os-release should fix this (it seems to), but I thought that the installer packaging should do this as part of the upgrade.
I read a forum post that suggested the new release is expecting to run on OpenSuse Leap 15.4 (as the new ISO appliance installs), yet most of the base appliance repos still appear to be pointing to version 15.3. Another Grommuinio Community Forum post suggested updating the Grommunio repo to use the 15.4 repository, so tried that on my upgraded version and then ended up with a mix of 15.3 and 15.4 versions of the Grommunio components. Listing the repos on my install showed that many of the base openSuse repos are still pointing to 15.3. At this point I decided that my linux knowledge was being stretched and the upgrade process had not been debugged enough, for linux newbies, so decided to put the upgrade to one side for the moment.
I did try doing another 'zypper ref' and 'zypper up' on a fresh clone of my live system after editing the Grommunio repo to use the 15.4 repository which also ran through without any new errors in the logs which did update the Grub boot screen correctly without needing to update the /usr/lib/os-release file. Another article suggested running 'zypper dup' but this just seemed to open another 'can of worms' with 'Problems' being reported for an number of the Grommunio files (can't remember all of them but Sync and Web were definitely mentioned). My inexperience with linux clearly now showing.
I then did a clean install of 2022.12.01 ISO into a new VM and imported emails from Outlook OST's (gave me a chance to play with the Grommunio import tools). The Webclient seemed to run OK and mails were viewable as expected. 'Zypper ref' and 'Zypper up' seem to work OK on this VM as well. Due to constraints of me having only 1 dynamic IP address an d needing tom keep my live system live I wasn't able to test full functionality of this new VM). I did some version checks between the various Grommunio components and found a number of discrepancies between the clean install and my test upgraded version. It looks like the new build requires php8 etc, which is present in the new ISO appliance but the upgraded VM is still appears to be using php7 which I believe is giving rise to various 'Problems' during the 'Zypper dup'. Not having enough knowledge/experience with linux to resolve this suggested I need to do more reading/testing.
Later that evening I saw that one of the regular forum posters mentioned that an upgrade process might be forthcoming in the near future, so decided to sit back and wait.