I'm having the same problem but now I'm doing a scrub and I see 155M/s speeds.
I reported this in a bug in 2019 but it was not addressed maybe I could create a new one.
[freebsd:/usr/jails/vm/ubuntu2 $]> uname -ar
FreeBSD freebsd.feuer.local 14.3-RELEASE-p7 FreeBSD 14.3-RELEASE-p7 GENERIC amd64
[freebsd:/usr/jails/vm/ubuntu2 $]> dmesg | grep da[01]
da0 at mrsas0 bus 1 scbus1 target 0 lun 0
da0: <ATA HUS722T2TALA600 MU03> Fixed Direct Access SPC-4 SCSI device
da0: Serial Number WM3324432FPK
da0: 150.000MB/s transfers
da0: 1907729MB (3907029168 512 byte sectors)
da1 at mrsas0 bus 1 scbus1 target 1 lun 0
da1: <ATA ST2000NM0018-2F3 EA04> Fixed Direct Access SPC-4 SCSI device
da1: Serial Number ZD423KY
da1: 150.000MB/s transfers
da1: 1907729MB (3907029168 512 byte sectors)
freebsd:/usr/jails/vm/ubuntu2 $]> zpool status
pool: zroot
state: ONLINE
status: Some supported and requested features are not enabled on the pool.
The pool can still be used, but some features are unavailable.
action: Enable all features using 'zpool upgrade'. Once this is done,
the pool may no longer be accessible by software that does not support
the features. See zpool-features(7) for details.
scan: scrub in progress since Sun Feb 22 19:40:44 2026
804G / 804G scanned, 545G / 804G issued at 155M/s
0B repaired, 67.76% done, 00:28:36 to go
config:
NAME STATE READ WRITE CKSUM
zroot ONLINE 0 0 0
mirror-0 ONLINE 0 0 0
gpt/zfs0 ONLINE 0 0 0
gpt/zfs1 ONLINE 0 0 0
errors: No known data errors
I reported this in a bug in 2019 but it was not addressed maybe I could create a new one.