My understanding was that there was some push back and political/police violence but the Chinese state largely let it play out and then within a month or two made mass arrests of the organizers.
This was a broadly supported movement, impressive in its size and unity.
The strategy Xi used was to not over emphasize the level of public support through direct confrontation - but to wipe out all resistance when the “controlled” energy of the crowd has somewhat dissipated.
Lesson for the current environment in the US: have a long term strategy tied to your goals, put very high degrees of pressure on specific state actors / functions that they cannot ignore or wait out
HK was economically dependent on China already, so their last struggle occurred too late, under the implied threat of the Chinese army moving in. The city government found ways to bring in Chinese police (or interior ministry troops) to overcome and outlast the protests.