So I checked with CX PR on accessing the lounges if you still carry an 'amber' code on the HK app (ie have been in HK for less than three days, bearing in mind that day 0 is your day of arrival), and here's the response:
The airline must scan an individual's LHS for passengers departing from Hong Kong and wishing to enter a Cathay Pacific lounge. If the passenger has an amber code, they will not be able to enter the lounge.