This usually happens when a channel lacks context or info about the creative value you’re adding to make the content unique. Check out these best practices and after making changes, you can re-apply again in 30 days: https://yt.be/help/reused-content …
Reused Content is not about Copyright (or permission, or fair use, etc) and is separate from YouTube’s Copyright enforcement – it’s part of the Content Quality section of YPP policies. Here’s more info and best practices to help you make changes: https://yt.be/help/reused-content …