Have you tired disabling "Adjust Display Brightness" or chaining the color profile for the display? Both of these are found in display settings.
http://osxdaily.com/2019/01/16/screen-flicker-macbook-air-2018-workaround-fix/
I can't duplicate the problem using Safari+Netflix. I only experience the flicker at a coffee shop, and only sitting in a certain place. I'm pretty sure this has to do with the light sensor that controls the display brightness.
Another possible solution is to try an SMC reset, which was recommended somewhere. It makes some sense because the SMC controls screen brightness settings.
https://support.apple.com/en-us/HT201295