Are mobile apps dropping UX in favor of super-clean interfaces? If so, why?

Today's mobile apps, compared to 5-6 years ago are way cleaner visually.

Nowadays you can find several popular apps with a way that is really so clean that there is no value proposition on the login screen, not even a single picture apart from the logo: check Twitch currently or Instagram login screens compared (attached).

I saw so many times apps with forms where the input rules were not visible, and you would only see the error after filling up everything and pressing the "proceed" button to go back and see the issue to correct.

Did I freeze on time? Why are apps dropping so much potential in UX for a super-clean interface?