The reason it doesn’t work with the instructions from the Pi-hole GitHub is because they assume you installed it directly on your sistem. But you installed it through Umbrel and on to of that, it’s in a container.
Unless you have the time to figure out how to update it yourself inside the container it is running in without breaking it the only thing you can do is wait untill the Umbrel Team upgrades it.
Unfortunately this applies to all Umbrel apps.