So is the Electrum server acting as a watch tower for Phoenix? Documentation isn't clear on the technical specifics of how the wallet doesn't need to be always-on.
This is what has been mentioned:
"Phoenix has been designed for less technical users, who don't know or want to run an always-on Lightning node on a server or to manage channels, with sensible trade-offs for those users."
https://phoenix.acinq.co/faq#can-i-connect-to-any-node-can-i-connect-to-my-own-node
"You can configure Phoenix to use your own Electrum server to watch the Blockchain and monitor your channels."