Chinese Communist Party dictates mainland China.
HK citizens feel they face a freedom crisis as Hong Kong is becoming increasingly closer to mainland China.
Anonymity in a protest and wearing a mask as a measure against tear gas are reasonable desires for protesters.
However, due to the fact that demonstration have escalated and become violent, it is inevitable that the Hong Kong police will suppress protests and maintain security.
Even from a global view, the Anti-Mask laws are enforced in many countries in the name of security.
Historically, it has been unavoidable in times of mass protest for governments to enforce a law forbidding rioters to wear masks in demonstrations.
For exsample, Anti-Mask Law in New York has been made since 1845.