Interesting to see F is back on 343 again!
I was looking up SIN-HKG flights on KVS close to Christmas and found F inventory on CX734 in multiple days and a 343 is listed as the operating aircraft! I double checked on Expertflyer and it was showing the same and then on CX website and it turns out to be a 77A instead.

Had a similar issue last week when my CX734, operated by a 773 mysteriously changed to a 330 on the GDS a few days before departure!