Did you read this guide about recovering funds of your node?
It is specified there where is located a latest version of channel.backup file.
Umbrel works in this way:
- user open or close channels
- umbrel has a script that makes a local copy of channels backup every time a channel is open or close (see in the guide where is located)
- after creating that file, the script also is uploading it to umbrel servers, as a secondary copy of it.
Users should download all the time they open and close a channel a copy of that file. This can be achieved by opening Umbrel dashboard - lightning - 3 dots - download channel backup. Takes exactly 5 seconds to do it. If you cannot spend 5 seconds from your life to save your channels, I don’t know why you are running a node.