The output of "smartctl --xall /dev/sdb1" includes
SMART support is: Available - device has SMART capability. SMART support is: Disabled Temperature Warning: Disabled or Not Supported query_cmd_support response too short Read Cache is: Enabled Writeback Cache is: Enabled
Interestingly, I haven't been able to get SMART data from my internal drives using gnome-disks (see https://bugzilla.redhat.com/show_bug.cgi?id=2303813 ) but I could using smartctl -a. With the portable drive, it's reversed, I get the SMART data from gnome-disks but not from smartctl -a or -x. Anyway, I doubt that has anything to do with this since that started with kernel 6.10.3 and the slow transfer problem started before 6.9.12.
The output of /proc/mounts includes
/dev/sdb1 /run/media/andre/Seagate btrfs rw,sync,seclabel,nosuid,nodev,relatime,space_cache,subvolid=5,subvol=/ 0 0