Best answer: Yes, HBO Max can stream in 4K resolution, and it finally streams some content in that higher resolution. Just not all of it. Your hardware may upscale things to 4K, but that's not the same thing.
HBO Max has all kinds of content from all kinds of places. HBO. Warner Bros. Comedy Central. DC Universe. TCM. Pretty much everything in the WarnerMedia catalog. But for the first seven months or so of its life, it topped out at 1080p resolution. That all changed in December 2020, when it streamed its first movie in 4K.
That said, HBO isn't all that specific about the exact resolution in which it streams. HD generally means 720p. Full HD, or FHD, would be 1080p. And that's what the newer top-shelf HBO Max content is streaming at. Older shows, like Friends, for example, also are streaming in 1080p, but obviously weren't recorded at that native resolution. So you'll notice.
Resolution is just one part of the equation, though. Bitrate is another. On an Apple TV 4K, we're seeing a bitrate of about 8.5 Mbps on a 200-Mbps connection. Results may well vary on other devices, but Apple TV 4K is about as good as it gets these days. (And it allows for easy benchmarking, so we can see what we're working it.)
That doesn't mean you won't ever see artifacting or pixelation. It happens, especially when a stream is just starting to spin up. And it also doesn't mean that there isn't room for improvement. Things can always get better.
But now that it's finally streaming some content in 4K resolution, HBO Max is more able to compete with the likes of Netflix and Amazon Prime Video.
