Companies started pushing E2EE a few years ago because users' private messaging data used to be a liability. Now that the data can be fed into LLMs for training and inference its value has gone up significantly, and the privacy and security tradeoffs are suddenly worthwhile.
PMs across the industry are pushing product decks with "conversational AI assistants" to get their next promotion. I've been in more than one of these meetings myself. If the data is encrypted then there's no way to build this kind of stuff.
Any e2e encryption provided by the same entity who fully controls both the blackbox clients, and the server in between, is just a security theatre that they can selectively bypass anytime with very little risk of detection. Not really much better than simple client to server encryption.
Truly safe e2e requires open source client provided by a trusted entity who is as much as possible independent from the one who provides the untrusted transport layer. Eg how pgp email works.
people who otherwise would have gone their entire lives without ever hearing about encryption were exposed to the term and the marketing convinced them that encryption and privacy was a valuable thing, even if they didnt fully understand the mechanisms or why e2e might not necessarily be very effective in specific circumstances.
later, when presented between option a and option b, where one has encryption and the other doesnt, they are more likely to choose the one with it ("well, if instagram and facebook use it and say it is good...")
between signal and plain text, it is easier to convince friends to use signal if they see positive marketing about encryption on other popular apps they use. it is easier to convince them to encrypt their backups before uploading them to their google drive. hell, its just a good conversation starter to introduce encryption/online privacy to people that never really think about it. that type of thing.
those same friends are not going to use irc regardless. not really a loss if it was never even on the table.
Whatever the cause, it sure sounds like it was a strange and unnerving experience.
Walking outside (after asking my wife if she could hear it): silence. Trees rustling, normal noises.
It was background noise. But inside the apartment that combination of different sounds was just right that it sounded like muffled music to me - but hence why I couldn't identify it, whatever was there was just me thinking I was hearing things.
Draw ones own conclusions about the relative technical plausibility of the events described by the OP (how would digital packet based audio experience a glitch which is structured as though you'd tuned into another analog radio station? It wouldn't: that doesn't happen and it isn't even a failure mode).
Obviously it involves trust that it isn't actually "we say it's e2ee but actually we also MiTM every conversation"
You are no more capable of spotting a deliberately concealed backdoor in a binary than in source code, there's simply no meaningful difference.
Eg. The Debian random number generator bug.
I can't say I really mind this change by Meta that much overall though. Anyone who's serious about privacy probably knew better than to pick "Instagram chat" as their secure channel. And on the other hand having the chats available helps protect minors.