What is this symbol that appeared on the inside of my car?

The windshield of my car got foggy on the inside due to humidity and I noticed this symbol on my front windshield. It went away when I wiped it, but showed up again the next time the windshield got foggy. Does anyone recognize it or know where it may have come from?

For context, this is a used car that I bought last summer. It’s a Subaru forester. I’ve never put anything there or stuck something that could’ve left residue, and it doesn’t feel like anything is sticking out.