Yes, Netflix has prevented streaming on its app for a long time, unless it runs via Google Home/Chromecast.
With Amazon Prime, I was able to solve it by installing an older app version (Nov. 2019 Apk), where the streaming still runs via Miracast.
I currently stream Netflix directly from the browser to the NeoPix (Windows 10 projecting to wireless display). That works without any problems.
Another option would be to attach a Chromecast to the projector via HDMI and then stream Netflix and other apps from the mobile phone via Chromecast.