Beginners can buy a slightly thicker fitness mat, but the thicker the better. It depends on your weight and exercise style, and you should choose materials if you have the conditions.
Normal weight, doing general yoga or indoor sports, 6 mm is enough. If the weight is relatively large, it can reach 8 mm
Cushions are used to absorb shock. Too thick cushion will reduce the stability of exercise and be easy to get hurt.
The mat for freehand exercise should not exceed 6 mm, and 1~3 mm is enough without harming the body.