Everything KDE--inclusing isoimagewriter--built from current git master. When I download the Fedora 37 KDE ISO (https://download.fedoraproject.org/pub/fedora/linux/releases/37/Spins/x86_64/iso/Fedora-KDE-Live-x86_64-37-1.7.iso) and open it with ISO Image Writer, it displays the "Could not verify as a known distro image." warning message. Nonetheless it lets me write the image to my flash drive, so this message is pointless, in addition to being incorrect.
Thia appears to be fixed in today's git master when I re-test it.