Thank you for your responses! Sorry for vanishing, life came up and I didn’t have time yesterday to do more troubleshooting.
The TLDR is I noticed how many threads there are on this exact problem and figured that even if I resolve it this time it will come up again, so I moved my instance to a slightly larger server with 35GB of space on it.
For anyone looking here for help with this exact issue who doesn’t want to upgrade:
./launcher cleanup was something I had already tried, it didn’t clear up enough space. I had also already done
sudo apt -y autoremove && apt -y autoclean
sudo apt clean
sudo journalctl --vacuum-time=1s
And again, it wasn’t enough. There was a lot (for a 25GB machine) of logs in journalctl, so absolutely check if that’s true for you, but for me it didn’t help enough.