Have any Mac users seen /Users/[username]/Library/Caches/com.adobe.LightroomClassicCC7/com.apple.e5rt.e5bundlecache grow out of control?

I’m the user the OP is helping. The cache grew to 865 gb! Alerted to the issue when Mail reported no room for messages..,Filled all the free space in drive rendering the computer virtually unusable until we found the source. Usual Mac disk space available did not pic it up. Found it through Terminal. Deleted cache and it grew back. Sitting with LR open, doing nothing,  and watching in Finder i can see it grow. I was in the habit of leaving LR open all the time, so I’m not going to be closing it and emptying the cache every time! That’s not an acceptable solution. And yes, I tried every method possible to rectify it! Adobe subscription has now been cancelled as i had paid the last 3 months for something I couldn’t use and that was enough for me, but hopefully this info will help someone down the track.

I've been watching this cache regularly for a while now, after it showed up in a disk utility I use as a "large folder" when it hit about 60GB. Here are a few actions that I've seen adding data to the cache:

Subject Masks

Background Masks

Landscape Masks

Distraction Removal (Reflections, People, and Dust)

Remove with Detect Objects checked

Lens Blur

Adaptive Profiles

These actions add data to the cache as soon as you choose them in LrC; that is, if you start to add a new subject mask but then don't use it, or there is no dust to remove -- you still get the cache entries written. With subject masks there's a behavior you can see: the first time you create a subject mask, you'll see "Detecting Subject" on screen for a several seconds. If you don't add that mask, or delete it after adding it, the next time you add a subject mask to that image, it will be a lot faster. That performance doesn't persist between sessions or even between module changes though.

I haven't seen the cache grow continuously without using a feature that updates it, but I've probably not found all the actions that might do so. I have seen it update cache entries for no obvious (to me) reason immediately after starting LrC and before I do anything, however, so that could be happening.

I've never seen entries get removed from the cache, except after an OS update when it gets flushed the first time I launch Lightroom and, say, add a subject mask to a photo. Lightroom software updates don't trigger a cache flush -- something I got to test when 15.5 came out a few days ago. Theoretically (I guess) we shouldn't have to be concerned about caches and MacOS should clear them to recover disk space when necessary -- but I couldn't test that for this cache without trying to fill up my system with cache entries. In other words, I don't know at what point Mac would say "I need to clean up some of these cache entries" other than after an OS update.

The problem with this particular cache is that it grows so quickly, especially since each use of a subject mask or landscape mask (for example) may add 100MB-300MB to the cache. It's easy to see how big it can get after you've edited a few hundred photos. While I've not had a problem after deleting everything under com.apple.e5rt.e5bundlecache multiple times, there could be implications to doing that that I don't understand.

There are similar caches for Photoshop (under com.adobe.Photoshop) and the Lightroom Desktop application (com.adobe.lightroomCC), but I haven't tried to figure out which functions update those caches since I don't use those apps very much.

It may be related to this thread: https://discussions.apple.com/thread/255835917?sortBy=rank

I checked it out. That folder is 1.9GB on my Mac. If I go into the folder to check individual subfolders, then I do see a few new folders created today. One folder is about 100MB, seven folders are about 80MB, two folders are about 25MB and the rest is just 64 bytes. The oldest folder is from 1st August, so it seems the cache is emptied regularly. Using the Adaptive Profile seems to trigger the creation of some new folders, adding a sky mask does not seem to add anything to this cache. After some tests the entire cache folder had grown to 2.64GB, so nothing out of the ordinary.