If you have a Windows 7 install on VirtualBox (VDI) or VMware (VMDK), you can convert it in 2021 easily:
Windows 7 does not natively support many modern virtualization drivers. To achieve "near-native" performance in 2021, the following are required: windows 7qcow2 2021
:
: Windows 7 does not natively include VirtIO drivers. To achieve high performance in a QCOW2/KVM setup, you must manually load VirtIO drivers If you have a Windows 7 install on
Windows 7 does not include drivers for modern virtual hard drive controllers. windows 7qcow2 2021
Can't install Windows 7 with q35 (SATA) (#55) - QEMU - GitLab
: While managing his virtual storage, Leo encountered a known bug of that year where some cloud providers would mistakenly revert disks back to a