why is Adobe holding so much memory?

I do not think this is of any concern. For a Mac, the bottom line is that there is zero need to worry about memory usage as long as Memory Pressure is green, at the bottom of the Memory tab in Activity Monitor.

I do see numbers like yours, but my theory has been that the memory shown for each process is not actually what it’s actively using in real memory. That it probably includes inactive memory that’s being handled in other ways, like compressed memory and swap memory.

Like other modern operating systems, macOS does not operate solely off of real memory. Most people know it can also use virtual memory swap files on storage, but fewer people are aware that macOS also compresses inactive data in memory to free up more real memory for active processes. macOS constantly and dynamically converts data among these states, as needed, to handle the current load.

To test if the numbers are all using real memory, I did a Select All in the Memory tab list, and copied and pasted it into a spreadsheet. Then I had the spreadsheet add up all of the values in the Memory column. (Where Activity Monitor listed GB, I converted to MB to be consistent with the smaller values.)

The total comes out to almost 39GB of memory seemingly “in use” for the 542 processes listed in Activity Monitor on this Mac. Now here’s the thing: This Apple Silicon Mac has only 32GB of unified memory. I have also seen times when Lightroom Classic itself is listed as “using” more than the 32GB in this Mac, but everything is running fine. Therefore, the memory values for each process in Activity Monitor cannot possibly mean real memory used, because the Mac doesn’t have that much. So my theory might be right that those numbers have to also include memory that’s allocated but temporarily stashed away as Compressed or Swap so as to free up more real memory for tasks that need that memory right now.

This is why a modern computer can run over 500 processes, with seemingly “no” free memory, yet the computer runs just fine with no lag. It’s because a large percentage of the memory you are looking at is not in active use at this moment, probably including memory pre-allocated for things like caches.

Also interesting to see that on my Mac, I’m not using Spotlight search (mds_stores) or the Finder at the moment, but they’re near the top of the list of 542 processes, and they’re “using” more memory than many other applications, more than Creative Cloud UI Helper (Renderer). And the Wacom Tablet Driver is somehow “using” more memory than the Music app that is playing right now from a large music library.