I believe what you’re seeing is the remnants of the pyramid after it was destroyed. It’s a shame because these pyramids are magnificent. Belize is open about letting travelers explore them. Probably will start locking them down now, like everywhere else.
I’ve been to the Mayan pyramids in Yucatan. They are larger and higher. They are still intact. Some may not be and are more crumbling. This photo has full overgrowth on top and its not that high.
There’s no before and after for this. I looked to see if there were any photos of this pyramid, but there doesn’t seem to be.
Not that I’m saying they ought to have removed gravel from even what is more akin to ruins of a Mayan structure.