Zbrush distorted mesh/ artifacts?



First of all thanks for clicking at my question. So I was trying to sculpt a very basic face using one of Zbrush default mesh. Everything was cool until I realized there is some kind of distortion or artifacts on the model’s lips.

This is the model before retopology

This is after retopology for a clearer view of the distortion

Do you know how we can fix this problem? I just started using Zbrush recently so everything is still so overwhelming haha. Thank you very much and have a nice day!