foo1.cs

private static bool IsPossibleCodeBehind(IFile file)
{
  return file is IFileImpl {SecondaryRangeTranslator: { } translator} && !(translator is IInjectedRangeTranslator);
}

foo2.cs

private static bool IsPossibleCodeBehind(IFile file)
{
  return file is IFileImpl { SecondaryRangeTranslator: { } and not IInjectedRangeTranslator };
  return file is IFileImpl { SecondaryRangeTranslator: not (null or IInjectedRangeTranslator) };
}