LOL, I think it's because of timing of the pre-production and also entertainment in Asia tends to be in waves and in this case, it all coincided. Kind of like how they released a whole bunch of time travel media of which Palace was the most popular example. The oversaturation led to rumors that Palace 2 wouldn't involve time travel and be an AU non-sequel that just shares a name but I think now they will include it after all and it'll be a direct sequel.