I develop a lot of applications as library as open source. Why? The question is, why not?

But, long story short, practically every library that I develop, target php 7.2 and higher (including 8.x). Why? PHP 7.2 is still strong and those libraries also work without any change with PHP 8.1.

In production my PHP is 8.1 (latest), while my code is +7.2

Also, there is not a huge change between 7.2 and 8.1, and most of the features are simply syntax sugar, so I can live with it.