That’s how it looks to me, yes. Mine has now reverted to null after doing the update:
installed_version: 154.07.28 'latest_available_version:': '' friendly_name: FRITZ!Box 7590 Firmware Update device_class: update
Interesting though that the current version info hasn’t updated yet…
Will make a note of the colon fix as it will need an update to the automation for the next HASS update.