The Foundation Brush by Yensa impressed Mikayla in her video review. As a first-time user of a foundation brush, she was initially concerned about its stiffness. However, she found the brush to be surprisingly soft and it didn't leave any streaks on her face. Mikayla was pleased with how well the brush applied the foundation, highlighting its effectiveness. Overall, the Yensa Foundation Brush seems to be a great choice for a smooth and streak-free application. However, the review does not mention any potential drawbacks or limitations of the product.