How can I stop my iPhone 16 Pro from dictating everything?

Setting up my new iPhone 16 Pro, I somehow did something so it will not stop listening and taking dictation. I have Siri set up to listen for Siri or Hey, Siri. But if I open the messages app, every word the phone hears--from me or someone else or even a video) is typed into the message. This seems to happen even if I don't touch the microphone. The Messages app is unusable--I can't delete what's going in fast enough to type the message I want. And tapping the mic icon to try to get it to listen to *me* changes nothing. Same thing when I try to use maps. Every word it hears goes in.

I've done internet searches and watched youtube videos . . . I guess I'm using the wrong search terms because nothing I've found works.

How can I get this to stop? I only want it to take dictation when I tap the microphone icon, and not every sound from everywhere. This worked perfectly on my old phone . . .

[Re-Titled by Moderator]