After extensive research, I have concluded that the Mesa Plateau F biome has somehow been removed. I have looked up many MCPE seeds that had them in earlier versions but do not now.
For Example: JackFrostMiner posted this 0.9.x video that has a Mesa Plateau F near spawn, but when you try the seed now, the terrain is the exact same but the Plateau F is unexplainably gone!

Jackfrostminers Video: https://youtu.be/DTdZQ19RrGg

The screenshot below is what it looks like now. In the video, there is a Mesa Plateau F right there.

SEED: 1734483989