For Windows guests, the machine version is pinned during creation, becauseWindows is sensitive to changes in the virtual hardware - even between coldboots. For example, the enumeration of network devices might be different withdifferent machine versions. Other OSes like Linux can usually deal with suchchanges just fine. For those, the Latest machine version is used by default.This means that after a fresh start, the newest machine version supported by theQEMU binary is used (e.g. the newest machine version QEMU 8.1 supports isversion 8.1 for each machine type).