JetPack/SDK Manager is a GUI frontend to the actual flash software. This has different requirements than the software being flashed. For an Ubuntu host PC, and JetPack 5.x+, you can use an Ubuntu 20.04 host, but not a 22.04 host (the software being flashed limits this; other non-Jetson software is why the GUI itself is compatible with 22.04, but not for flashing a Jetson).