It’s actually main memory as /run in in memory.
You haven’t describe what else you have set up besides piaware, so impossible to guess what the issue is.
You can check /run for big files i suppose:
sudo reboot
sudo apt install ncdu
Then when the problem occurs again:
sudo ncdu /run
Could also be some program using lots of memory.
Honestly if you don’t have a clue, better to reimage.
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