There were some tightened security features on both Android and iOS in that phase.
Basically a lot of really dark patterns were killed. A free casual game reading all your files. A game with media access being able to "track" you from location information in your photos, without any file or location access. A social media app could be pasting your password from clipboard to their servers. A messaging app which you gave cam/mic access once to could be recording you while it's in background, and converting your audio information via their speech to text.
So a lot of the changes have been around making this behavior really visible. Sure, any app can access your cam/mic, but there's a green light every time it does. Sure, it can copy/paste from clipboard, there will just be a little notification each time.
10-13 (haven't used v14 yet) were all just completely forgettable (mostly UI changes, no significant new feature).