I dunno what all those other sites run, but we host our own instance and @darix personally maintains the package. I don’t think there is anyone more qualified than him, he is a literal wizard.
Note that discourse offers free instances to FOSS projects. Maybe those other projects are using that.
just checked those instances:
<meta
name="generator"
content="Discourse 3.3.0.beta1 - https://github.com/discourse/discourse version 91f0c717209ade996b9c83b26024c3522e1dd5c3"
>
so yes as @paperdigits said it is probably the free discourse for FOSS projects hosted by discourse itself.
as soon as 3.3.0 is released we will update to that.
That explains it, thank you.
–
Ian