Is anyone actually surprised by this? They've devoured the whole internet for training already, the stream of shit coming in from users is the only way to hoover up more training data.
six months later
Quietly update the ToS to allow them to retroactively use all of your history and data going forward, attempt to fly under the radar and/or gaslight users that it's always been that way
I don't think people understand that while consumers are dumb, uneducated, and broke, enterprise is a cash cow with a experts and a legal team.
If you serve them, like Google does on a massive scale, these ToS "gotchas" will do you in faster than you can say "lawsuit".