Are you aware you dont need to understand the actual data to build data on a consumer. Even when its end-to-end encrypted proton still know your IP, the IP you’re trying to access, number of packets (data size) your online times etc.
So while they cant read your facebook messages, they know how often, and at what times you use facebook messenger, netflix, youtube etc. And they can turn that into a profile on you that they can sell.
Yep