It's not just you! I'm running Sequoia 15.1.1 on a MacBook Air M3 15" and ALL external USB drives fail to eject and therefore require Force Eject:
- USB-C drives
- USB-A drives plugged in using Apple's $25 USB-A to USB-C adapter dongle
- All drives formatted APFS
FSCK is not running. I've killed the Spotlight indexer but that hasn't helped.
Sometimes restarting the Mac will allow me to eject the drive in the first moments after restarting, so clearly something is kicking in early in the boot process which is preventing the drive from being ejected safely.
This is a new Mac purchased within the last few weeks and set up from scratch - that is, I didn't restore from a backup of any sort.
Every autumn brings a new version of MacOS and every autumn weird bugs such as this crop up. Clearly Apple's attention is focused elsewhere. It worries me that such basic things are being broken every year. After 40 years of MacOS, you'd think such basic features/functions would be protected from being broken by ongoing OS development: Apple excels in so many ways, yet the fact they can't protect their own OS from this sort of bugginess is more than a little worrying.
I've used the FeedBack Assistant to submit a bug report. Perhaps you can too. It won't be fixed if we keep it quiet: the squeaky hinge gets the oil! You can find official bug reporting details here.
All the best!
Peter