Yeah, I see this repeated a lot but I haven't really noticed a difference. Maybe I'm just not picky on the topic. But my understanding was it was never traditional SD, but 720p.

Regardless, I use firefox and Amazon, Disney+, Netflix, HBO Max all work reliably for me. I believe there was a period were a couple of them didn't work for a month or two on linux when they came out but I wasn't subscribed to them then and they've always worked for me.