At best it’s circumstantial anecdotes pointing to Facebook extracting topic metadata out of your convos. This can be done clientside, no decryption necessary. (And it’s easy to prove that it’s being done if that’s the case)
E2EE plus arbitrarily invasive clent-side sniffing/reporting should not be considered "E2EE" by any means. Even if reports to the mothership are strongly encrypted (at which point it becomes harder to determine what's in the reports).
I didn't claim they are. But they can. And without transparency, I have very little inclination to trust. I find it plausible that they'd scan for keywords and phone home when they get hits -- advertising businesses are not known for their scruples and fb has not distinguished itself in that regard. Once that machinery is in place, it's ripe for abuse. I don't claim any proof it's happening, but it would be naive to blindly trust that it isn't.
