You are, by design. Beeper gets around the e2e encryption by just running WA themselves on their side; there is no other way for them to be doing what they say they are doing…
I run several bridges from my home. With End-to-Bridge Encryption enabled this gives you about the same security guarantees as E2EE with a second device added (Signal Desktop, etc). With Beeper you can do the same, IIRC.
Their value proposition then hinges on how good their clients can aggregate conversations and different chat networks, I guess.
So _you_ run the bridge, not them?
But then _you_ need to make sure it's available 100% of the time?