It may be too early to draw conclusions, but if we take into account that mainland Chinese cannot invest in these ETFs, and that the HK ETFs market is estimated at around $50 billion, the conclusion would be that they are a small dwarf compared to the US ETFs market, which is worth trillions of $.
Even considering total population between those country (7.5M vs 334M[1]), the difference is very big. I wonder whether ETF isn't popular choice among HK investor or HK investor simply being cautious after looking Bitcoin price post ETF on US.
It is possible that the timing of the launch has something to do with it, because everyone obviously bet on the halving, and on the other hand, the majority does not even understand what is actually happening then. Maybe now we will have to wait for the halving to start giving its first effects, so that the investors start getting back into the game again.
Most investors still do not want to be exposed to Bitcoin for too long, even though it would very likely bring them a good profit.