Hmm, it looks like Group #25 is actually group #26, probably starts with group zero?
Yea the numbering is probably off by one.
Bike is probably off so the contactors are open, that measurement will be garbage in this case.
I don't know enough to say whether that amount of imbalance in one cell group is fatal. It's very possible a proper bottom balance would recover things to a normal level if that cell group isn't actually damaged and just fell weirdly low. There is of course also a slight chance that going too low on SOC (maybe less than 10%) would brick the pack or cause that cell group to do very bad things. I'd say Stark probably has the best advice for your situation but that might be tricky given I assume you have no noticable impact to performance on the bike.
The latest version of the Stark app (2.6.0) has some internal code they added which shows the VCU is now reporting a bunch of battery fault flags like "battery high diff", "battery cells incomplete", etc. The first one would likely be flagged for your bike and the latter would likely be flagged for the two folks who had missing cell groups. I assume in the (hopefully near) future these flags will be used to display warnings in the Stark app, but I didn't see that added as of the moment.
Are you using the iOS or Android app? I'm going to push a new iOS release right now (probably will take at least 24hr for Apple to approve) since that can be done while the primary app release review is ongoing. For android I need to wait as Google has no mechanism for releasing a new (even just test) version while they are actively reviewing a previous version (for the full public app-store release). The new app version shows these flags in the service -> battery page so you can at least check and see if the VCU has also flagged your battery.