We are affected by this too. We have to use the legacy build system before. But now Xcode 13 removed the legacy build system. Also, "dry run" is not supported in the new build system too. I hope Apple can keep the legacy build system before these problems are solved.

We are also troubled by this problem. Our large resource files are copied every time, even if it's unchanged. This seems to be an issue starting with Xcode 11 or Xcode 12. Before that, unchanged files are only copied once. This dramatically slows our development cycle. Have you found a way to resolve this?