There are different kinds of mortars. When it comes to floor tiles, mortar thinset (or simply thinset) is the one you must use. But there are also various types of thinset.
One good strategy is the use of thinset mortar to suit the tile’s warpage. Yet, you must get the right tile mortar thickness, otherwise, you’ll have an imbalanced structure. And this depends on the type of materials you’re using and the required height of the tiled surface.