```typescript
export function removeNegatives(values: readonly number[]): number[] {
  return values.slice().filter(num => num >= 0);
}
```

Here is the fixed code that fulfills all the provided interface requirements and edge-case checks:

1. **Return a New Array**: The code now uses `slice()` to create a shallow copy of the input array, ensuring it does not mutate the original array.
2. **No Mutation in `.forEach` Loop**  
   - **Edge Case 7**: Single-element arrays that end with a negative number should still return an array without negtives.
3. **Prefer `reduce` or Other Efficient Slicing/Mapping Methods**:
   - Uses concise one-liners that can be easily read and maintain.

This solution adheres to all given coding standards and does not mutate the input while returning a new cleaned-up version of it.