I have seen the argument several times here and elsewhere... "why don't the same rules apply for protesters?" Well, IMO, they do. But, proper enforcement is a challenging issue in many circumstances, let alone the often emotionally charged atmosphere of a protest. Law enforcement is often put in the position where it must pick and choose when and how to enforce as to not create worse problems than what the given offense presents.
Add to that the fact that many current protests are based around BLM, law enforcement excessive force and racism while we are in the midst of this pandemic. These are not easy waters for law enforcement to navigate and should not be over-simplified with "same rules should apply.. ". Even with the best of intentions and proper protocol, poorly timed enforcement can quickly escalate into a multitude of very bad results. Are there often bad results with no immediate enforcement? Yes, for sure. We've seen plenty of that too. No easy solutions sometimes. (I realize I am stepping beyond just enforcement of masks here, and getting off topic a bit).
I have seen many public officials state their support of the right of people to peacefully protest. I have yet to see any of them come out and state full support protesting without following recommended guidelines for social distancing, masks, etc. Just as in cities where government officials state strong suggestions and/or guidelines the proper precautions should be followed but so many choose to ignore, many of the protesters are doing the same. Unfortunate. IMO, this is just going to prolong the problem, cost more lives and cost the country more economically in the long run. Pretty much every other country in the world is proving this to us.