Cards have been in vogue for a while and I can’t recall the last time I saw super hard corners on a design system. It’s been a thing since at least Apple filing that patent on rounded corners.

You're absolutely right (as they say) - https://www.folklore.org/Round_Rects_Are_Everywhere.html

I don't think it's just the base rate of rounded corners though, these posts feel like the AI tends to spit out a bullet point list of features, like you'd see on an AI readme where each feature has a tangential emoji, then for a website puts them in a grid of rounded rects

Look at the website you're on