Same for my 4TB Seagate HDD connected via Thunderbolt, it is ejected on my iMac with Mojave (where it was connected directly), as well as on my MacBook Air M1 with Monterey (where it is connected via a Thunderbolt to USB-C adapter, the one from Apple). I just wonder if it would be better just to buy a new case with USB. I used it as backup for my iMac but when I eventually needed a backup it just stopped half way; luckily I had a backup with CarbonCopy. After stopping, it started to be ejected; I reformatted it but it is ejected all the time anyway; really annoying. Apparently, same problem with an Legato Thunderbolt SSD on Monterey)