iPhone is asking for passcode without even trying Face ID first. How to stop?

TL;dr:

How to stop iPhone from asking for passcode when it has not even tried Face ID, not even once?

(& I was already using it mere moments ago.)

Fully:

So I used my phone all day today, then I put the phone in my pocket & headed to the post office. I only pulled it out to quickly check the time once or twice.

When I got back home, I pulled out my phone from my pocket & put it on the counter.

About 5 minutes later, I picked it up, & it would not unlock with my Face ID, even though Face ID worked all day today. Huh?!?!?!

It refuses to unlock unless I input my passcode. I did not turn it off. I did not update anything. I did not have repeated (or even a single) failed Face ID attempt(s).

Service can be weak in some areas but, I did not drive through the local dead zone; so, it was connected to the internet the entire time, at least one or 2 bars.

So, I don’t really care why it is doing this, I just want it to stop doing this. How do I get it to stop doing this?

[Edited by Moderator]