Not Really, but yes, when you are heating the beard, it could be a little bit of damageable to the facial hairs. In the above list, we have only told you about all the safe brushes. These are using negative Ionic technology, Ceramic, and best for the beard.
You can’t fully protect your beard for the damage caused by excessively straightening it, but you can mitigate a lot of it by only straightening your beard when its clean and moisturizing it with coconut oil afterward.
So you must make sure about the health of your beard hairs while straightening it wash it before using a straightener and then moisturize it after with coconut oil is best practice.