I suspect this may be related to poor btrfs maintenance.
See the folowing comment in another topic:
That post offers several links which I suggest you follow to understand how this can be the problem.
A forum search will also reveal many other cases where this has been discussed:
Regards.
A few more quotes from other topics to enhance understanding:
As these suggest, your disk consumption is already critical for btrfs; and ext4 might also begin to struggle with the amount of space you have available.
There is a fundamental difference between how space is managed with btrfs and ext4, for example.
Avalable space when using btrfs spans all partitions (much like Apple’s apfs). Let’s say for the sake of argument that your system reports 20 GiB available – for btrfs and apfs, that’s 20 GiB available across all partitions – unlike ext4 which would only refer to available space on the current partition.
One might think that’s a lot – in modern computer systems, it really isn’t.
The moral to this story is to never overfill your storage. Other files systems also have recommended maximum usage limits – for Microsoft’s ntfs it’s generally about 75% before the amount of data you have stored becomes detrimental to system processes and general maintenance requirements, such as defrag, for example.
Path to a cure:
I’d strongly suggest moving some data from /home to external storage (perhaps a USB HDD formatted as ext4) and always be conscious of disk usage – especially that of /.
Anecdotal:
We all have reasons for the way we choose to configure partition sizes – I’d configure a new installation Manjaro (if on a 500 GiB disk) much like this:
| Partition | Size (approx) |
|---|---|
ESP |
300 MB |
/ |
100 GiB |
/home |
300 GiB |
swap |
32 GB - 64 GiB |
/other |
Remaining space |
Even so, it’s easy to discover that a 500 GiB HDD/SDD isn’t quite as large as we imagine it to be; wherever possible, I install any OS to a (minimum) 1 TB disk to help avoid such problems.