A "client" stole my test project, posted it, and now my own portfolio channel is getting copyright claims.

Hey everyone, I just experienced a new level of freelance hell and wanted to hear how you handle this. A potential client asked for a test video edit. I wanted to show my best, so I spent a lot of time on pacing and smooth transitions. Sent it over, and they instantly ghosted me. No contract, no payment. A few days later, I uploaded the video to my own channel to showcase my portfolio. Boom. Copyright strike. It turns out they just stole my test work, uploaded it to their channel as their own, and now the a