Massive cache files attributed to CloudKit.

This is a continuation of the thread Massive cache attributed to CloudKit - Apple Community. There was no solution there and I could not post any comments so I'm creating this new thread.

So here are the symptoms I was facing:

my old external HDD failed one fine morning and I had my photos library stored on it. I truly don't mind as I keep a copy of the library on iCloud, on Google Drive and on my Raid 1 NAS so I only use the library on the Mac to browse my pictures fast. So when the HDD failed I was expecting it to do so. I then replaced it with an external USB3 SSD and created a new library file and let it download the entire library on the new drive. After a few days, I thought the library would have been received by the photos app, so I opened up the external SSD to see how big the library had gotten! To my surprise, it was no bigger than 20 GB while my main NVME SSD had lost more than 200 GB of space. After several restarts, the external drive would not enlarge the photo library file and instead, the main NVME would start filling up to the point it could fit no more files and then empty itself again only to repeat that. In the meantime, the photo library file would stay stuck at about 20Gb of space.

After careful examination I realised that the issue was due to the fact that the folder /Users/[username]/Library/Caches would fill up and occupy about 200Gb of space, only to reset again. More specifically the folder /Users/[username]/Library/Caches/CloudKit/com.apple.cloudphotod

I decided to erase my photo library file and reset it again. The moment I did this, the whole issue went away. The Caches folder went back to 2GB of space and my mac had 200Gb of free space again!

The new library file seems to be filling up and I'll let it download all the photos to see how it will handle it. I believe the issue was due to the new external SSD reaching high temperatures and shutting off due to thermal protection protocol. That incosistency might throw off the photos settings that are then unable to backup on that drive again. If it does it again I suppose I need to go and purchase a new one.

In any case if someone had similar issues, I'd love to get feedback on the issue.