It's a bit of a bummer that the OnePlus 7 is only able to stream Netflix at "HD" resolution — that's below the full 1440p resolution of its beautiful display, after all. But if you decide to unlock the bootloader for future root/ROM adventures, then you'll have to make do with just non-HD 480p Netflix streams.
For the unfamiliar, Netflix and some other services like Hulu and Amazon Video use a Google-provided DRM solution called Widevine, which has multiple levels of security. A higher "L1" level of Widevine is required by Netflix for 720p HD playback. For a while, OnePlus phones didn't even support L1, though all phones since the OnePlus 6 have shipped with it. And like its predecessors, the OnePlus 7 Pro loses that L1 support if the bootloader is unlocked. In such cases, the devices fall back to (insecure) Widevine L3, which Netflix only uses for lower-quality 480p playback.
Not all devices lose Widevine L1 when the bootloader is unlocked — for example, the Pixel 3 XL last year — but OnePlus devices do, and based on reports, the 7 Pro is no exception.
A previous version of this article referenced a 720p limit, as measured by certain videos in the Netflix catalog which show their output resolution in the video itself. We spoke to a representative from Netflix about this and were told that resolution varies based on encoding, with some titles in certain encodings not available at higher resolutions (specifically, this pertains to VP9 encoded content). The performance of such videos is not representative of the rest of Netflix's catalog or capabilities, which offers up to 1080p on capable devices, including the OnePlus 7 Pro.