Issues with Windows 10 - system temporary Files

So, I'm running Windows 10 and my system temporary Files are constantly eating up my hard drive space—it's like 25GB gone just like that.
I usually clear everything out using CCleaner, which works fine for a bit, but as soon as I reboot, the system fills it right back up and I'm stuck with zero disk space again.
Is there any way to actually turn this off so these system temporary Files stop piling up? And honestly, what even is this stuff anyway?
Thanks!

...on my Windows 10 - system temporary Files have always just been stuck in the KB range, honestly. I've never even seen them hit MB, let alone GB.
Since you brought up CleanMyMac, try running an Analysis first, then click those "temporary files" and check the "details"—or just drop a screenshot here so we can see what's up...