Also is this a thing that was triggered once, or reproducible every time you run it.
In the latter case it might be very hard to track down.
I checked and as part of the qemu verification I do run&migrate older guests in newer hipervisors.
I do not yet do vice versa in a lot of tests, so even if this issue ends up non reproducible I might add that to our regular test set to be executed more often.
Also is this a thing that was triggered once, or reproducible every time you run it.
In the latter case it might be very hard to track down.
I checked and as part of the qemu verification I do run&migrate older guests in newer hipervisors.
I do not yet do vice versa in a lot of tests, so even if this issue ends up non reproducible I might add that to our regular test set to be executed more often.