After 5 hours/2 days working with Apple tech through phone, we did everything mentioned above and even more at least twice, still NOTHING WORKS. We had to send iMAC back to a local store and see if they have a better solution and voila~ after spend $267 for changing the wireless card, bluetooth/airdrop/mouse finally all function well. It seems that the Monterey system has bugs with the wireless/bluetooth card. It seems when updating OS, it's time for the Mac store to get profit from old customers.

It is March 2022 and just update to Monterey version 12.2.1, MAC still has the same problem on mouse response and bluetooth connection. Does Apple really tried to solve this?