Mac doesn't automatically recognize my audio input device anymore

I am a podcaster, and I use my 2020 MacBook over Zoom to record some of my interviews. My Mac was on an older iOS until recently, and then I got automatically updated to Sonoma (which I didn't want).

After the update, I discovered that when I connect my audio input device via USB to support a dynamic microphone, my Mac doesn't automatically recognize it anymore, even if I think it's selected for my audio. I have to manually go into Audio/MIDI Setup and also my System Settings to change everything manually. I also saw that for some reason, my iPhone is showing up in my settings as an audio input device, which never happened before, and which I don't want. I would like to remove it.

I recently ruined a podcast interview because I thought I was recording into my dynamic microphone over USB during the Zoom call. It was only later that I discovered that my Mac had defaulted to built-in computer audio, even with all my gear plugged in like normal. My recorded audio ended up sounding terrible and echoey and full of static, whereas normally it sounds clean, warm, and radio-professional. I was appalled, and spent hours trying to fix it. But as the saying goes, "garbage in, garbage out."

This seems like a bug, and it continues to happen, much to my dismay. In my many years of using a Mac, I've never had this issue before. How can it be fixed?