This can be a bit confusing. When you uninstall packages, new snapshots get created, which take up more space.
Additionally, snapshots are incremental. So, if you were to install openSUSE and then install 5000 packages one-by-one, you’d have 5001 snapshots, but it would still only take up about the same amount of space as what has been snapshotted.
What makes snapshots take up lots of space, is if there’s lots of differences between snapshots. So, if you install texlive and later uninstall it again, it still has to keep the entirety of texlive in your snapshots.
So, the best way to get back disk space is to delete old snapshots. That just tells it that you don’t care about whatever differences may have existed between snapshots at the time.