Why won’t Siri wait for me?

Whenever I try to use Siri, I run into two frustrating issues:

Siri often misses the first few words I speak, despite waiting for the ding before I begin.
Siri often stops listening when I’m in the middle of my sentence or question.

The first problem is likely a bug, but the second is because I speak slowly to Siri and often need a few seconds to think of even very basic words.

Back when I could initiate Siri with the Home button, I could hold the button until I was finished my sentence and Siri would listen until I let go. Without the home button, I don’t know what to do.

Addendum: I’ve just discovered that if I invoke Siri by pressing and holding the power button and don’t let go, Siri continues to listen even when I need a few seconds for my words to come out. Not sure why that had not dawned on me other than that I had been invoking Siri with “Hey Siri” and by tapping my AirPods. I guess those aren’t options for me.

※