Snapcraft removed all my data without --purge
Solution 1:
Ok, turns out that the snapshot was indeed saved it just didn't automatically restore it when I re-installed. The way that snapcraft makes these backups is detailed here: https://snapcraft.io/docs/snapshots
Looking at my saved snapshots showed that it was saved:
~ » snap saved andre@andre-office
Set Snap Age Version Rev Size Notes
31 brave 51.5m 1.24.82 112 1.72GB auto
So I just had to run, sudo snap restore 31 to get it all back.