I've been running a TB2 24tb G-Speed Shuttle XL on my iMac for a few years now. On Mojave I never saw the 'Disk Not Ejected Properly' message. Worked perfectly as expected. Once I updated to Catalina it started showing up every few days when the computer was asleep. I might see 1 or 2 messages when I logged on in the AM. I updated to Big Sur hoping this bug was resolved and now I see 10-20 of these messages upon awakening the computer. If I eject the drive before putting the computer to sleep it will still result in 10-20 messages. The only "fix" is to physically disconnect the drive or turn the iMac off. This is not ideal as I am a video editor and backups are scheduled to run at night when I'm not using the machine. I have spent hours researching this issue and tried every tip/fix I have seen. There are simply no energy settings, cable, reformatting, resetting PRAM etc etc. that resolves the issue. What I have learned is: There are a ton of people that have this issue. The issue is 100% with Mac OS. Seems to be getting worse with each update. Is not on Apple's radar (which seems very un-apple) This is such a bummer that it would be the only subject I would discuss with Tim Apple at a social gathering.