The app is (and was) a TWA. I had to push an update as Google changed their requirements (again). It is a torture to work with them. Regarding your data they may have flushed the local settings while doing the update (I saw that in the past). Did you use OneDrive, Dropbox or urzadirect to save your collection?
Without that I cannot really help
Unfortunately, I didn't use those options. I did an export at the beginning of September, it will limit the loss to Dominaria+ some other hundreds of cards. Better than nothing.
Anyway, thanks for your fast answer!
Really sorry but this is out of my control