It might but every CA I know uses intermediate certificates, so there's absolutely no guarantee of the future. Maybe Kestrel is "smart" enough to load and serve the correct intermediate when switching to the other CA (probably because ASP.NET doesn't have an older intermediate cached/stored somewhere), but what if that CA also switches intermediates?
The issue here is ASP.NET for some magical and unknown reason sends the utterly incorrect chain while not instructed to do so (according to the currently viewed code). Why would this be any different with a different CA? ASP.NET would still be a #@*(+&#@ piece of software.
It seems ASP.NET brings all the same related Windows cert problems with it.
Perhaps searching the forum for help on Windows and R3 might shed some light.
Maybe. But, when I read the Kestrel developer threads about this they knew they only sent a leaf and even developed a fix to send a chain. But, it has not been deployed. It seems different than what IIS does in that regard.
I did not read the Kestrel code - just the dev talk.