The Netflix button on your remote may be stuck or misbehaving. Try taking the batteries out of the remote and using the mobile app as a remote. If the problem goes away, you'll know the remote is the problem.
Roku Mobile App - Free for iOS® or Android™ | Roku
Roku Community Streaming Expert
Help others find this answer and click "Accept as Solution."
If you appreciate my answer, maybe give me a Kudo.
I am not a Roku employee.