In Walk Navigation mode with gravity enabled, the jump height is often inappropriate for the scene that you are viewing. This is a small feature that lets you change the jump height in modal walk navigation as you go, i.e. if there are varying elevation changes across the scene. Pressing '.' increases and ',' decreases the jump height (because these keys are the same for most layouts). Pull Request: https://projects.blender.org/blender/blender/pulls/109827