From what I gathered here and on Halo Reddit, the game for some of us with OG Xbox One’s now looks like it’s running in 720p since the Overtime update. Anti-aliasing also appears to be off. I captured the footage below after I switched the Xbox One’s DVR to 1080p, so you can see what I’m seeing (its default is 720p, which doesn’t really capture the crappiness).
(make sure you set the video to 1080p in the settings at the top right corner of the video on Dailymotion)