What makes you think it hasn't long been using a large language model for it though? Maybe not Large Language Model, the term seems to have come with ChatGPT et al., but Google's been doing machine learning for a long long time; the transformer architecture paper (kind of the groundwork for the current wave) was published by a Google team in 2017.

A lot of new Google features are branded 'AI', because it's so hyped it has broad consumer awareness, but a lot of Google features for a long time have used AI and just been brandless or at least 'AI'-less features.

It started about a month ago for me. I am subscribed to emails from an IT as a Gig platform called Field Nation. Thought I might pickup a bit of side work but never did.

Recently it started adding them to my calendar and there is no way to turn off this feature without also turning off useful features such as package out for delivery notifications.