In short - massive demand from HKers from travel means there are very few seats available, and when they pop up they are taken very rapidly. Even if you are finding Y availability you would be, if transiting via HKG, saving a fortune as flights are very expensive here currently. Plus Cathay is still flying a vastly reduced schedule based on what they previously had - though they are trying to add planes as soon as they can train/certify the crew.

In short - you need to wait a year or more to get back to more normal availability, change your routing to avoid Cathay, or just pay an inflated cash fare.