Depends on what distro you’re on? You say the deb version is 4.0 and flatpak is 5.0, suggesting you may be on a long release distro?
I’d favour the Deb version as it’s official for your distro. The flatpak version is unverified; it’s extremely unlikely Virt-Manager is compromised or will cause any issues but virtual machines do have security risks.
Also problem solving issues with the flatpak version may be more difficult as you have a whole layer potential issues in the sandbox on top of all the other issues people can have around KVM/QEMU. But you could install it, if it works great, if not, revert to the Deb version.
Depends on what distro you’re on? You say the deb version is 4.0 and flatpak is 5.0, suggesting you may be on a long release distro?
I’d favour the Deb version as it’s official for your distro. The flatpak version is unverified; it’s extremely unlikely Virt-Manager is compromised or will cause any issues but virtual machines do have security risks.
Also problem solving issues with the flatpak version may be more difficult as you have a whole layer potential issues in the sandbox on top of all the other issues people can have around KVM/QEMU. But you could install it, if it works great, if not, revert to the Deb version.