From their temp folder, which is completely reasonable.

while I sneer at the unwashed masses clearing temp stuff by hand in 2024, I'm in the same boat trying to declutter stuff in my Mozilla/Thunderbird profiles :( ...

Doesn't the built in Windows disk space cleanup app actually clear temp as well?

Not C:/temp no, it clears %temp% which is usually squirreled away as C:/Users/<username>/AppData/local/temp

Several lifetimes ago I was looking at a Solaris server with very limited available space on the root partition and realized that someone had deleted the kernel file, presumably trying to solve the same problem.

I really hope it wasn’t me.