"Other" Storage Continuously Full: How to Manage

I am the only user, went through a javascript program and have design files from the Adobe suite.

I'm now 95% sure there are temp files somewhere being created on loop. I had "update automatically" on which I usually turn off for this reason.

I have most of my files backed up now individually but I will likely do a backup to the external too.

It's absolutely absurd that "System" and "Other" cannot be drilled down even if the items are disabled for edit. Since "Other" fills back up so quick, I'm not even sure if it can handle an OS reinstall or full time machine backup even to the external drive.

Deleting things only frees up space for a small amount of time before it refills in other, so I have purchased a new machine arriving tomorrow, and will have to take this one in to apple. Or burn it with fire. TBD

Update: I'm backing up files now on an external HD and still dealing with the issue. I am going to pivot slightly as I think it might be pinpointed to Firefox, dumping small cache files that add up. Still, the 'other' is still dominating when I delete things and fills right back up as soon as the next day.

I changed my search query to "recently created" instead of large file sizes, since those are already vetted, and it seems to be constantly dumping what appear to be session files to firefox temp directories.

If anyone has tips, by all means please chime in, I already did a screenshare with an apple remote advisor who was also stumped.

Thank you but this is the roundabout reply for everyone.

1. Other storage is easily identifiable in Containers and Caches among others
2. Time machine local snapshots is Off
3. Applications/Downloads and Mail is correct, at 50GB... the other 450GB is the issue
4. Other is now continuing to fill up even when new things are deleted

This is the best resource I have found so far:

https://discussions.apple.com/thread/252939770

Saved files are estimating at 50GB. There should be absolutely no reason temp files take up ~450 GB remaining. That ~Library screenshot only accounts for around 40GB on the largest directories, so 50GB local and 40GB temp is only 100 GB total. How is the other 400 GB not viewable? Probably because it would expose Apple's own problems I would imagine.

I cleaned out 5GB with a remote advisor today, and 2h later "Other" now has it refilled. Final recommendation was to back up externally then reinstall fresh iOS and load in that backup. I'm a web developer and designer so this is a must, and even that wouldn't guarantee the fix.

I really don't want to have to ship this machine off again, last time was a terrible experience.

Apple is telling me to update device (2015 MBP) and also iOS. I doubt it would be smart enough to erase temp files but the machine has beome unusable.

I'm looking into purchasing a 2020+ MBP but seriously considering bailing on Apple due to this nonsense.

Thanks for this information, would you suggest doing a full time machine backup on the External HD or just cherry pick the file/directories I normally work with? I have whittled everything down to the bare bones of apps and what I previously stored, I'd like to prevent re-loading the problem files at all costs.

I'd prefer not bail on this machine yet, but have not had catastrophic issues like this. At this point it's affecting my workflow significantly and am seriously considering moving away from Apple.

Luckily it's not dead yet and the most important files are backed up. There is no room to re download Monterey update as its 12.5 (~16Gb) unless I can DL it to the external HD and boot from there.

Surely someone has dealt with this before? Caching seems way off: WatchOS? I don't even use the one I have.