I have always noticed Pride Rock looks noticeably different throughout the franchise, and even Pride Rock looks different during the finale of the first film where it goes from like
this, where its peak looks quite smooth and not as roughly steep and curvy, to
resembling its original look at the start of the movie in a matter of minutes.
But the biggest reason for its diverting appearance is the difference in art direction during the production of the films and
The Lion Guard.
Lion King art director Andy Gaskill and production designer Chris Sanders deliberately modeled the look of Pride Rock based on the natural mesa found in Hell's Gate National Park. I don't know too much about
Simba's Pride's art direction, but director Darrell Rooney stated in the
making-of documentary that Pride Rock was seen from its back side to reflect its shadowy side so different background artists created new background shots to reflect that sentiment. In the
production notes of
1½, director Bradley Raymond stated "Our art director James Gallego was able to capture the look of the original film. He spent countless hours studying the original, but also brought his own artistic perspective to our movie."
The Lion Guard is obviously going in its own distinctive art direction.