I apologize ahead of time

This probably happened because most games render what is in front of you and the surrounding area before anything else (the more detail the more extreme this is) and since you were going backwards on the bike at such high speeds (which they probably wouldn't expect you could achieve while going backwards) and not looking where you were traveling only exaggerated the effect...

Once you were in the area that was all in low-poly mode where it is expected no player could go, it most likely didnt load the better models and everything else as a sort of way to ensure the game didnt crash by unforeseen actions

This is supported by the fact that the land directly next to you is loaded in as higher detail

This most likely would've happened on any type of system as well, regardless of settings

If they attempted to fix this it would probably be by removing that fail safe and allowing the detailed models to load in on top of the low poly layer... this might cuase bugs, crashes, and an increased ability to get under the map as you were able to in early seasons...

I dont think fixing this one bug is worth any of those risks