Comment 2 for bug 1902654

Thanks for this good report!
And also thanks for providing the workaround for anyone else running into this.

The old types should (tm) not change due to the compat layers that on any change ensure that former types have the old values set. That is an issue within qemu.

I don't see yet why that would be specific to windows guests, but maybe their drivers trigger something Linux wont.

P.S. I know you now got it migrated, still I'd strongly encourage to bump to a more recent machine type at e.g. a planned service downtime window or such. You just don't want to carry things forever.