Seriously, what the fuck? I thought it was some kind of user interface glitch so I looked it up. Nope, they're A/B testing this shit.
Found this brilliant statement by Youtube on the matter:
Now note that we are deprecating one sorting option and that is by oldest video at the channel level. But don’t panic, you can still view the oldest video of a channel, by scrolling through it’s content’
Oh, yeah, just scroll to the bottom. Silly me, I guess I'm just a stupid idiot for not realizing the option was redundant since I can simply take the time to scroll through potentially thousands of videos.
Why are silicon valley tech people such freaks?
YT videos have changed over time as people play into the algorithm with flashier thumbnails and more shocking click bait titles. YT celebrities have popped up since I started watching videos back in the aughts. The eternal September of the internet is introducing new viewers to a world of ad watching and the marketers that make these decisions told the devs to remove the oldest to newest sort algorithm so new watchers will slough off to Bethlehem to be born as ad watching junkies.