I have a nvme drive in ACASIS enclosure. System Settings/Thunderbold/Enable Thunderbolt devices is on, the device is authorized and trusted. Disk & Cameras/Device Auto-Mount/All Devices/On Attach is set. When I connect the drive to a thunderbolt port on my laptop, the drive is mounted, though I have to type in a password in an authorisation popup dialog. That is a minor inconvenience - when the device is trusted, why the password requirement?
However, to unmount it, I have to type umount from a terminal window. The panel’s Disk & Devices does not see the drive. I can configure the dialog to see All Devices and the disk will show up, but then there is no Unmount option.
When I connect that drive through a USB3 hub, everything works as expected.
Nothing to do with the device itself.
The action of mounting requires privileges.
Though you can change this if you want - I dont suggest doing so.
The archwiki does have a method for only automatically connecting thunderbolt devices though, which would at least be more secure than simply allowing any mount without credentials.
https://wiki.archlinux.org/title/Thunderbolt#Automatically_connect_any_device
I know almost nothing about thunderbolt, but I wonder if maybe this troubleshooting section is related?
https://wiki.archlinux.org/title/Thunderbolt#PCI_buses_are_not_registered