After doing mobile dev that has worked directly with the Android Camera API, it shows. I believe Snapchat notoriously was held up, back in the day at least, in rolling out Android features due to how much of a mess it was.
Bluetooth has traditionally been another disaster zone. The low level APIs for interfacing with hardware shows a distinct lack of care for how the developer experiences things.
And on a meta level, either I'm improving way more than I give myself credit for, but whenever I dive under the hood these days of certain Android libraries, the underlying quality and elegance of design seems to be decreasing over time and questioning how certain PMs let some instances of kludges past their review process that I, who will never, ever pass a Google interview process, would reject completely out of hand if someone put them in a PR to a codebase I managed. I'm noticing a certain amount of increasing Reflection usage bleeding into libraries these days that you would expect at a widget factory who lost the original source code, not a FAANG company inside their own core platform. It betrays either a loss of control of the situation by product managers, or, more likely, teams are increasingly not able to interact across project departments and collaboration is being replaced with increasing inter-team hostility/indifference.