Netflix and all other streaming services use DRM to provide content. Firefox might have different DRMs from Chrome, even worse if you are on linux. As far as I know reading from other posts, there are several DRMs with different “tiers” of encryptions, lower tier are less trusted so websites only give them lower quality content, but they have more open licenses so it’s easier you’ll find it on an Open Source browser deployed on linux. I don’t know if there are ways to use different DRMs, maybe proprietary ones