I think it does actually no one except them can read them. If someone else can, then by definition it's not end-to-end encryption.
From https://www.definitions.net/definition/End-To-End%20Encrypti...
> End-to-end encryption (E2EE) is a system of communication where only the communicating users can read the messages.
E2ee means only the messages themselves can't be intercepted and read. But if anyone can actually prove fb acting on message contents, I suspect the EU banhammer would be interested.
But if the message is copied, read, analyzed and sent further on behalf of a third party before encryption, then that puts that third party in the middle between the sender and the recipient. A man in the middle directly undermines e2ee: "no one else reads your message".
It doesn't matter if the third party made the messaging app or not. What matters is whether information in your messages is accessible to anyone besides you and the recipient.
This said, analyzing messages for the purpose of ad display is creepy, whatever the way it is done.
Notice that "ends" in "end-to-end" are users, not applications. When an application forwards things to an entity, then that entity becomes an "end" of the conversation. When it displays a message to the user, the way the user wants, then the user is the end. When it processes the message and delivers results to Facebook, the way Facebook wants it, then the application makes Facebook the "third end".
In such scenario, Facebook had intercepted the message, just chose to forward only some extracted information (which may or may not be enough to reconstruct the original). This does not match the definition of "end-to-end encryption".
That's not right. First, it's technically an impossible, since users can't do encryption themselves - it's the application that does it. That's where the e2ee boundary is.
Second, we've got e2ee communication between non-user entities as well. There's are servers using for example zerotier which communicate e2ee through other nodes. Third, applications can definitely send the data to other parties automatically. WhatsApp executing backups as configured does not make it not e2ee.
We know the app decrypts it to display it. But if the app decrypts it to send it to the parent company, then it is by definition not end to end encrypted anymore.
If the app decrypts it, analyzes it and sends information about the message to the parent company, then the same thing is happening. The parent company is reading the message, INSTEAD of E2E encrypting it. It doesn't matter whether that reading happens on device or on the company's servers. E2E means the company is not reading it.
It’s possible that this data harvesting ad company has redefined what E2E means (to them) to advance their business interests.
HTTPS is E2E between the client and the server.