How to use Collision Mask on TileMap Physics Layer?

Help
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1

Godot Version

4.2.1

Question

If I create a Physics Layer on my TileMap and set the Collision Mask to 3. Then I set my CharacterBody2D Collision Layer to 3 (with a CollisionShape2D), there is no interaction between the character and this Physics Layer PhysicsMaterial.
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I want certain tiles to slow the character down and add Y-axis velocity while moving on them. (Picture below is Tileset Physics Layer property)
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I understand you can achieve this by effectively flipping which Node handles this functionality. I could set the Collision Layer to 3 on the TileMap physics layer and have an Area2D on character set to Collision Mask on 3. Then handle this problem via code within the _detection functions. But then I don’t understand the use-case for Collision Masks on TileMaps themselves.

All these properties on the TileMap make me think I could use it this way. If this is not how it works, then what is the point of Collision Masks and PhysicsMaterials being on the TileMap itself?