Today I learned: How to enable the BTRFS quota to see the space utilization of snapshots.
I am using BTRFS snapshots to have easily accessible jump points, in case something goes awry. I use them both for the root partition, and my home partition.
The other day I wanted to manage said snapshots and realized, that by default, no disk utilization was shown, which made it hard for me to clean up as intended.
So I ventured onto the Internet to search for a solution and I found it. I do not remember the initial source, where I found the information a few years back, but I linked the official documentation above, which contains the command to enable the quota: btrfs quota enable /. And that's it. I ran the same command for the /home subvolume and after that, snapshots do also report their disk utilization.