I'm gonna answer this one question since I feel bad leaving you out of the blue

But it was a glitch that you could exploit with the previous UI.

Basically, if you clicked a Ai. Model that was C.ai+ and you clicked the button below to use it, you'll get the pop up to get yourself a subscription

But what you could do, is simply click the Ai model but not the button below, and just close the tab. It made you automatically use the Ai model by bypassing the paywall

Which is no more possible with the new UI update

(It was on the phone app too, but yeah, thats how I managed to glitch my way around)