Well, that's scary. I just checked, and I had "everyone" selected. So I changed it to "contacts only". Here's how to find your AirDrop settings from
Apple Support:
"How to adjust AirDrop settings
To choose who can see your device and send you content in AirDrop:
Go to Settings, tap General.
Tap AirDrop, then choose an option.
You can also set your AirDrop options in Control Center. Here's how:
On iPhone X or later, or an iPad with iOS 12 or later or iPadOS, swipe down from the upper-right corner of the screen to open Control Center. On iPhone 8 or earlier, swipe up from the bottom of the screen.
Press firmly or touch and hold the network settings card in the upper-left corner.
Touch and hold the AirDrop button , then choose one of these options:
Receiving Off: You won't receive AirDrop requests.
Contacts Only: Only your contacts can see your device.
Everyone: All nearby Apple devices using AirDrop can see your device.
If you see Receiving Off and can't tap to change it:
Go to Settings > Screen Time.
Tap Content & Privacy Restrictions.
Tap Allowed Apps and make sure that AirDrop is turned on."