Thick Yoga Mats
Most yoga mats tend to be about 3-4mm in thickness. This is because it provides a good balance between cushioning and support/stability. When the amount of cushioning is increased, stability decreases, meaning it can be harder for you to balance. Mats with more cushioning are recommend for people who have joint issues or injuries to better protect them.
There are some thick yoga mats from yogaaccessories.com that also do offer stability because the material used is denser.
You just want to be comfortable & stable during your practice, so if you find that on your thicker mat, then that’s perfect.