Even stranger then. Just to make sure I'm not missing something, I just tried this on my Mac:

  $ cargo --version
  cargo 1.86.0

  $ cargo new hello-rs
     Creating binary (application) `hello-rs` package

  $ cd hello-rs && cargo build --release
     Compiling hello-rs v0.1.0 (/Users/int19h/src/hello-rs)
      Finished `release` profile [optimized] target(s) in 0.73s

  $ ls -la target/release/hello-rs
  -rwxr-xr-x@ 1 int19h  staff  468608 May 20 20:16 target/release/hello-rs*

  $ ./target/release/hello-rs
  Hello, world!

Are you sure it's not because the package in question does some kind of weird custom build steps?