That's not a bad idea, I'll see what people think. Note that clicking on the unsubscribe link will unsubscribe you to whatever comms preference was specified in the sending and tell you what it was.
Hey, Proton CTO here. There was a bug, and we fucked up. Support should have reported it up the chain and acknowledged this. Things happen, especially at scale, but we take comms consent seriously and will fix it.