How is this a scam?

So this just happened. Is this a scam? And if it is, then how exactly does this work?

His profe and friends seem super legit.

Earlier this year I had a similar guy contacted me. He needed help with his NFT marketplace - He wanted to add 3D models support there. So we discussed some features for 2 days, then he sent me a gitlab repo and asked to implement a test feature (to show that I'm capable of). He didn't even asked to commit - just record a video of it working. I checked the repo for any kind of malware very carefully, and it was clean. So anyway, I did what he asked for, sent him the video. And that's it. He gone silent. And after a week I noticed that the chat disappeared with all message history.

Do any of you guys have a clue what's happening? Btw I still have that repo saved locally, should I post it?

So this just happened. Is this a scam? And if it is, then how exactly does this work?

His profe and friends seem super legit.

Earlier this year I had a similar guy contacted me. He needed help with his NFT marketplace - He wanted to add 3D models support there. So we discussed some features for 2 days, then he sent me a gitlab repo and asked to implement a test feature (to show that I'm capable of). He didn't even asked to commit - just record a video of it working. I checked the repo for any kind of malware very carefully, and it was clean. So anyway, I did what he asked for, sent him the video. And that's it. He gone silent. And after a week I noticed that the chat disappeared with all message history.

Do any of you guys have a clue what's happening? Btw I still have that repo saved locally, should I post it?