Bhyve NIC Passthru broken

Hello,

Starting a vm (FreeBSD 13.2) with passthru NIC results a constant flood of
error messages on the host (FreeBSD 14-CURRENT).
The NIC refuses to work in the vm (it works on the host if I turn off the
passthru).
This problem is persistent since 13.1-Release.
(Sidenote: the passthru mostly works under the EOL 13.0-p13 with the same
config, only occasionally showing the symptoms after multiple vm reboots,
and a host reboot solves the problem unlike in 13.1-release 13.2-release
and now 14.0-current)

Ruling out NIC/board hardware fault and specific NIC driver problems, I've
tried with the following NICs:
- Intel I350-t4
- Intel 82580
- Broadcom BCM5720

...in different desktop and server boards (with the latest BIOS):
- Asus M5A99X EVO R2.0
- Asus M4A87TD EVO
- Asus KGPE-D16

  # freebsd-version -kru
14.0-CURRENT
14.0-CURRENT
14.0-CURRENT

  /boot/loader.conf:
vmm_load="YES"
nmdm_load="YES"
hw.vmm.amdvi.enable=1
pptdevs="8/0/0 8/0/1"

  # vm passthru|grep ppt0
ppt0       8/0/0        Yes          82580 Gigabit Network Connection

  the vm config file for vm-bhyve:
loader="bhyveload"
cpu=2
memory=4G
disk0_type="virtio-blk"
disk0_name="ptproba.img"
# igb0:
passthru0="8/0/0"
uuid="2333ba09-dfe1-11ed-9ed6-9c5c8e54ad77"

vm-bhyve.log:

Aug 03 02:25:16: initialising
Aug 03 02:25:16:  [loader: bhyveload]
Aug 03 02:25:16:  [cpu: 2]
Aug 03 02:25:16:  [memory: 4G]
Aug 03 02:25:16:  [hostbridge: standard]
Aug 03 02:25:16:  [com ports: com1]
Aug 03 02:25:16:  [uuid: 2333ba09-dfe1-11ed-9ed6-9c5c8e54ad77]
Aug 03 02:25:16:  [debug mode: no]
Aug 03 02:25:16:  [primary disk: ptproba.img]
Aug 03 02:25:16:  [primary disk dev: file]
Aug 03 02:25:16: booting
Aug 03 02:25:16: bhyveload -c /dev/nmdm-ptproba.1A -S -m 4G -e
autoboot_delay=3 -d /root/vm-bhyve/ptproba/ptproba.img ptproba
Aug 03 02:25:22:  [bhyve options: -c 2 -m 4G -AHP -U
2333ba09-dfe1-11ed-9ed6-9c5c8e54ad77 -u -S]
Aug 03 02:25:22:  [bhyve devices: -s 0,hostbridge -s 31,lpc -s
4:0,virtio-blk,/root/vm-bhyve/ptproba/ptproba.img -s 5:0,passthru,8/0/0]
Aug 03 02:25:22:  [bhyve console: -l com1,/dev/nmdm-ptproba.1A]
Aug 03 02:25:22: starting bhyve (run 1)

The first few dozen messages are like the followings (couple of hundred
lines):

ivhd0: EVT INTR 0 Status:0x1a EVT Head:0x0 Tail:0x10]
  [CMD Total 0x24] Tail:0x240, Head:0x240.
ivhd0:  [Event0: Head:0x0 Tail:0x10]
        [INV_DTE devid:0xa0 addr:0xfdf9103300 type:0x3 tr:0]
ivhd0: EVT INTR 1 Status:0x1a EVT Head:0x10 Tail:0x20]
  [CMD Total 0x26] Tail:0x260, Head:0x260.
ivhd0:  [Event0: Head:0x10 Tail:0x20]
        [INV_DTE devid:0xa0 addr:0xfdf9103300 type:0x3 tr:0]
ivhd0: EVT INTR 2 Status:0x1a EVT Head:0x20 Tail:0x30]
  [CMD Total 0x26] Tail:0x260, Head:0x260.
ivhd0:  [Event0: Head:0x20 Tail:0x30]
        [INV_DTE devid:0xa0 addr:0xfdf9103300 type:0x3 tr:0]

...then the constant flood (about 35 lines per second in /var/log/messages):

ivhd0:  [Event63: Head:0x3e0 Tail:0x8d0]
        [INV_DTE devid:0xa0 addr:0xfdf9103300 type:0x3 tr:0]
ivhd0:  [Event64: Head:0x3f0 Tail:0x8d0]
        [INV_DTE devid:0xa0 addr:0xfdf9103300 type:0x3 tr:0]
ivhd0:  [Event65: Head:0x400 Tail:0x8d0]
        [INV_DTE devid:0xa0 addr:0xfdf9103300 type:0x3 tr:0]

Any idea?

Best