I am also having this problem and the only thing that I've changed, other than updating to the latest release, is I swapped 2 drives over to ZFS. And my ZFS memory is constantly 99% full.
So as I don't actually have any use for ZFS, I'm going to switch back to xfs.
There is some discussion I saw on Reddit about increasing the ZFS memory size if you choose to go that route, if that's your same problem.