If the numbers were all that is wrong, that'd be OK. But it fails to list all data -- so the only way to navigate to the missing PRs is to know their number, and manually inserting the right URL (or to go to another PR, and then edit the URL in the navigation).
Sorry, but I don't think there is any way this can be classified as "not actually a bug"
GitHub stability has been bad for me. And recently even the data they show me in the web has been unreliably.
Since yesterday, me and several colleagues noticed that the pull request lists on the website are incomplete, across many repositories. For example, on https://github.com/gap-system/gap/pulls it says "Pull requests 78" in the "tab list", but the PR list view reports "35 open" (the number 78 is correct, and confirmed by e.g. `gh pr list`)
which is also driving me nuts because it frequently fails to update the issue and PR counts when I close issues or PRs. Only a hard reload, or closing the tab and opening a new new one, fixes it.
I find it strange to compare "math" with one programming language. Mathematics is a huge and diverse field, with many subcommunities and hence also differing notation.
Your rant would be akin to this if the sides are reversed: "It's surprising how many different ways there are to describe the same thing. Eg: see all the notations for dictionaries (hash tables? associative arrays? maps?) or lists (vectors? arrays?).
You don't have "the manual" of programming languages.
"
Maybe because tons and tons of software build with GNU make, not with Ninja, and if you want to be able to build that software, you need GNU make?
Also, Ninja by itself is not really a replacement for GNU make. Rather it's a tool one can build such a replacement on, so the comparison is a bit off to start with...
Sorry, but I don't think there is any way this can be classified as "not actually a bug"