Detected unknown airtag- weird red lines and I don't know what to do—HELP!

I received two separate notifications of an unknown airtag detected near me. It's weird because at these times I am home and NOT moving. I tried googling about this but I still don't understand what it means. Do the red lines mean that the air tag was moving back and forth from my home? Does the icon mean that is where it currently is or where it started? Is the airtag being detected in my house? No one owns an air tag in my home.