This is very unlikely. If they use the Safetynet API provided by Google (and why should they not), your phone tells the Google server whether your phone is okay (this includes root and other things) and the Netflix server would ask Googles servers whether the client is acceptable. Changing code in the app won't help much because the check is serverside.

Actually the check is a combination of serverside and client side. The server generates a random binary with a predictable output. The client then executes the binary and verifies its output with the server. It's a very clever trick and nearly impossible to spoof.