All external drives I have, both powered and portable, are dropping off Mac Studio M1

That’s hilarious! Is there a sticker on the drives that says "Does not behave badly"? If not how do you even know without Apple telling you which drives might work? All my drives/cables have worked just fine on everything BUT my Mac Studio. So, no, this is directly on Apple.

This is a wide spread problem in the OS. My OWC thunderbay 4 with a thunderbolt4 to a thunderbolt3 adaptor always unmounts after random lengths of time.

The only solution I've found is to install an app called Amphetamine which keeps the drive mounted by doing a random read at a fixed interval. The prob is that your computer will never go to sleep so you'll need to shut down/ boot up every time. Hope Apple figures this out soon.

In order to meet ever-more-demanding Energy Star ratings, Modern Macs drop USB power when they sleep.

Some drives tolerate this just fine.

Bus powered drives are especially awful, and some self-powered drives also do not tolerate the power drop as well.

If this happens when the Mac is awake and not sleeping then it still may be a cable issue. I had two drives that worked fine on my older Mac but with my new Mac Studio and new Mac Mini M1 they would drop off. I went through several cables before I go a robust connection. With one drive I got an official Apple cable that was rock solid. These later Macs and latest OS seem very finicky.

You are assuming this is an issue under Apple's control. I think you may be mistaken.

There are drives that follow Apple's recommendations and do not exhibit this Bad Behavior. I recommend you chose one that works properly.

I remember when I first got my Mac Studio in April 2022 I was having similar issues with my hard drives. It seemed to occur after I'd put the Mac into sleep mode and then woken it up, the drives just wouldn't stay awake. Since then I changed my spinning hard drives for SSDs and I never put the Mac into sleep mode, I just leave it on 24/7 and I don't experience any external hard drive issues any more.

I'm not sure if this is the same issue, but it seems to me that ever since I installed this latest version (12.6.5) I have had to wait for ALL of my external drives to spin up before things like Open... or Save... dialogue boxes will work. I used to only have to wait for the one drive in particular that I was working on (or in the case of saving, it would still show all of the mounted drives, and only when I chose a sleeping drive would that one drive spin up... now I don't even see the list of mounted drives until they have all spun up, even if I want to save a file to my internal SSD drive).

Also, I doesn't feel right that the accepted answer is to use some 3rd party software. There absolutely appears to have been some kind of change with this latest OS release, and it is frustrating the he-ll out of me. Have you experienced this all-at-once spin-up issue too?

Make sure you are running with the latest macOS update. :)