One reason you're see these anthems sung in Hong Kong malls is that malls are private spaces where the police for the most part can't enter. This gives the people gathering some measure of protection against a hostile police force. (Also, A/C and good reverb)https://twitter.com/KongTsungGan/status/1172111121676791808 …
We might start to see that soon! They are generally a step behind, but it's an excellent question