Issue creation endpoint has long supported preset parameters through query string, like this:
However, issue template will override the provided body in query string. You can observe the behaviour with the link above. They have an issue generator elsewhere and is using query string for new issue. The said behaviour renders it unusable.
I’m not sure it’s a bug or feature.
If it’s a feature, then I guess it’s a mechanism to enforce issue template. However, IMO query string should take precedence.
People won’t deliberately use query string to evade issue template, cause it’s troublesome. So when query string is set, it’s almost for sure a legit use case, like what I mentioned above. I don’t see the point letting issue template take precedence here.