What is the UseShutdownTimeout behavior?

[prcdpr]

I'd like to ask how exactly ASP.NET Core UseShutdownTimeout() timeout works.

What is the shutdown order? From my observation:

First, all pending requests have to be processed and finished. After timeout, they are force cancelled
After that, ASP.NET Core starts stopping all IHostedServices with StopAsync

Does UseShutdownTimeout() apply to 1+2 steps all together?
Let's say I set shutdown timeout to 10s.

Do I get 10s timeout on pending requests + 10s timeout for StopAsync on IHostedServices, effectively 20s?

I noticed StopAsync on IHostedServices isn't launched while HTTP requests are still running.