As said in the comments, having different tires in common in MTB, and is also discussed in the context of gravel racing.
The principle is: grippier tire front, less rolling resistance rear. The reasoning is that there is more weight on the rear, so most of the rolling resistance is mostly influenced by the rear tire. But when you brake or corner, the weight is transferred to the front. Having grippier tires allows to have more control when you need it, but because. Because there's less weight on the front rear when riding, the impact on rolling resistance is lower.
So having a semi slick front and a gravel tire rear might not be the most optimal combination.