Apple's hypocrisy is a longstanding issue with regard to their apps vs 3rd party apps. As I recall when the Green Bubbles first happened in messages someone pointed out that Apples own design guidelines specified a minimum contrast in colors or they would reject apps, and the green bubbles with white text did not meet that threshold at the time, and it stayed that way for quite a while. And for all I know the light themed version of the app still does (I have mine on permanent dark theme).

https://medium.com/@krvoller/how-iphone-violates-apples-acce...