The fix in mingw-qemu-ga-win-102.4.0-0.el8

Verify with this latest build qemu-ga-win-102.4.0-0.el8.noarch.rpm

version:
kernel-4.18.0-312.el8.x86_64
qemu-ga-win-102.4.0-0.el8.noarch.rpm
qemu-kvm-docs-6.0.0-19.module+el8.5.0+11385+6e7d542e.x86_64
RHEL-8.5.0-20210611.n.0

step to verify:
1. boot up win2016 guest with serial and qga.
2. connect with guest and execute qga command.

Actually result:
{"execute":"guest-get-devices"}
{"return": [{"driver-date": 1621123200000000000, "driver-name": "Red Hat VirtIO SCSI pass-through controller", "driver-version": "100.85.104.19900", "id": {"device-id": 4168, "vendor-id": 6900, "type": "pci"}}, {"driver-date": 1621123200000000000, "driver-name": "Red Hat VirtIO Ethernet Adapter #2", "driver-version": "100.85.104.19900", "id": {"device-id": 4161, "vendor-id": 6900, "type": "pci"}}, {"driver-date": 1621123200000000000, "driver-name": "VirtIO Serial Driver", "driver-version": "100.85.104.19900", "id": {"device-id": 4163, "vendor-id": 6900, "type": "pci"}}]}

Expected result as above.

Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (virtio-win bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHEA-2021:4341