My terminal prompt has a weird, unfamiliar name in it. What's up with that? Breezy's iPhone?

This is the beginning of all my terminal prompts.
First, I'd check what WiFi access point your Mac is connected to.

One explanation for your screenshot is that your MacBook is acquiring (or has recently acquired) its IP address from a DHCP server on the device called Breezys-iPhone. That's most likely to happen if that iPhone is acting as a tethered hotspot, and your Mac is connecting to it rather than your usual WiFi access point.

You can find additional information about the hostname shown in the terminal prompt in the answers to this question.