Normani is so underrated vocally. She definitely needs to work on her breath control when performing live, but she has an incredible range and can do so much with her voice.
Her whistles aren't as agile or flexible as Mariah's but it's still pretty damn impressive.
The Better Together or Mirrors notes didn't sound like whistles to me. More like falsetto notes, but this was very clearly a whistle tone. Slay a little Normani