Smooth and flatten tools destroy a small rectangle of certain areas

In certain areas of my map, the smooth and flattened tools take away a rectangle of the terrain in a way that is really annoying to deal with, it doesn’t really change when I mess with brush size or strength. It’s only in like two places, but they are critical spots, and I’m getting a bit tired of just avoiding the problem by closely using the sculpt tool (which works normally in those spots.) Including before-after pictures showing the damage done by the “smooth” tool.