I had the same problem, again after being a user for years. I ended up eventually rebuilding the system on xfs, ditching Snapper and the vagaries of btrfs. Not every release is solid though and you can go a few iterations before hitting a really good one. I've been on Leap 42.1 for a long time now.

That hit me for the first time 2 weeks ago. I spent a good 4 hours troubleshooting it. None of the tools or commands for analyzing disk usage counted the snapshots since it was in a hidden directory. Stupid glob star. 400GB of snapshots later I was back in business.

> I would part ways about Snapper though, by default it periodically fills the root partition, preventing normal booting

I have been there, too. It was very annoying.

Fortunately it happened to me on a sunday morning when it was raining cats and dogs outside.