If what you've outlined in red is water damage, why is it so irregular instead of showing a true "level"? What kind of liquid behavior would be a few inches thick but leave such an irregular mark around the base of the walls and stone box? Especially up there at the level of the KC?
I explained this before. The water was not standing still. The "waterfall" marks also show that quiet a lot of water was coming out of the shaft so it was restless with a lot of waves. That's how I interprete those marks.
It's often said that the pyramid was flooded, but I believe that there's even more evidence that the Pyramid was DESIGNED for water to flow through.
There once was a very important clue to be found in the Great Pyramid, real evidence: The Great Step, what was originally a huge V-shaped block.
This was not just a worn out stoneblock but originally designed in a V-shape. Look at how straight the triangle is:
In modern times it looks like this:
They destroyed one of the most important pieces of evidence. These people call themselves egyptologists but don't even recognize what is really important.
It's also possible of course that they did it on purpose, who knows.