EK ever since the onset of Corona have made their crews do a 26 hour duty. They are not using two crews either - the same crew work the inbound and outbound flight. It’s unrelated to the new testing procedure for aircrew in Hong Kong. Terrible working conditions for the EK crew.
Whereas I would certainly not defend EK employment practices (especially for cabin crew), my information is that this is patently untrue.
There has been one instance of the same crew having to work both the inbound and outbound to HKG and that was when the HKG authorities changed the quarantine rules whilst the inbound was en route to HKG. There has been a similar single occurrence on a New Zealand bound flight.
At the moment certain destinations are flown with an additional turnaround crew, others (presumably based on corona infection rates) are 'back to normal' where crew go into a hotel (although they are asked to stay in their room).