Brass brush on a drill would probably melt into plastic fast. But a handheld one would work ok, or steel if you need more persuasion and aren’t worried about scratches.

What’s under the caulk? If it’s ceramic tile, you can probably get away with a brass cup brush in a drill. Test in an inconspicuous area first obviously, but it should be less likely to scuff up the surface as something like scotchbrite.

I had it happen last week. I got a “we see you’ve received your package, how do you like it?” email. Except I hadn’t. Tracking showed it dropped off 2 days earlier. My office door is open to a busy sidewalk and often unattended so I assumed the worst.

Finally found the culprit on camera. When the carrier left the package, they put it on top of a pile of other packages. As they were leaving, a gust of wind blew it straight into a nearby trash can. Where I happen to put all the empty packages, so it didn’t look out of place. And of course that was the day the trash gets taken out.

Kind of comical in hindsight. Just glad it wasn’t really anything important.