Hello and welcome to PSG.
Please understand that there are literally thousands of different brushes on the internet and virtually thousands of other techniques that may involve combinations of textures and brushes mixed together to create any given effect. Unless the brush used in the image of question, contains clearly identifiable characteristics that can be immediately identified, it would incredibly hard to identify. One method that has worked well for me is to contact the original artist, if one can be found, and simply ask. Otherwise, identifying the brush or the technique used in any random image is a matter of guessing, experimentation, and trial and error.
Hopefully someone may recognize the brush or technique. But I wouldn't expect exact results from your inquiry if any at all. Good luck!