Thanks for trying to help out.
I’ve emptied the trash, but I only had a couple of text files in there.
Googling further, I encountered mentions of btrfs balance problem, such as here: linux - btrfs: HUGE metadata allocated - Super User
Running the suggested diagnostic command, I get:
[user@fedora /]$ btrfs filesystem df /
Data, single: total=111.62GiB, used=85.61GiB
System, DUP: total=8.00MiB, used=16.00KiB
Metadata, DUP: total=3.00GiB, used=2.74GiB
GlobalReserve, single: total=241.16MiB, used=0.00B
Seems that metadata is pretty close to being full, and may have been full before those prefixes were deleted.
Running the proposed solutions btrfs balance start -m /
and btrfs balance start -dusage=5 /
resulted in this:
[user@fedora /]$ btrfs filesystem df /
Data, single: total=95.62GiB, used=65.98GiB
System, DUP: total=32.00MiB, used=16.00KiB
Metadata, DUP: total=2.97GiB, used=1.12GiB
GlobalReserve, single: total=201.72MiB, used=16.00KiB
So, my data usage went down by 20Gb, and the metadata went down…
I’m not really sure what happened here. Should I be worried any further?