I'd be surprised if they were really going to sniff traffic and dump that into training runs. 99% of traffic is going to be encrypted these days. Probably not very useful.

You're talking about a company owned by one of the richest "tech bro" out there. He's not just an ISP, he's a visionary (for better or worse) with a lots of ideas.

TLS payload is encrypted, but meta data (such as SNI and other fingerprints) is not. These meta data could still be valuable for someone who know how to utilize it.