I don’t live in Boston anymore but I did the same thing. My town worked with a local energy supplier to set fixed rates through 2024. Clean Energy Choice sent a mailer basically mimicking the language and I opted in to their service instead of the local towns. I noticed my energy bill went way up (doubled while the usage stayed about the same). Luckily it was only a few months so I fixed it, but definitely felt like I got scammed.

Update: After switching, my supply cost went from $0.328 per kWh to $0.143 per kWh.