Why the open interest of October BTC futures contracts is high, but the trading volume is declining?

The open interest and trading volume of the BTC derivatives market increased significantly in October, especially in the options market, where the open interest increased by 107% (US$6.3 billion), which is close to the highest point in history. Among them, the most popular option contract seems to be For call options with an exercise price higher than US$100,000, the open positions of call options that expire at the end of the year are approximately US$250 million to US$350 million.But it seems that the transaction volume is declining. Why is this happening?