My speculation is, that's many containers of blades with immersion cooling put into racks. I don't know how many of them are actually filled with blades, but all FC now need to do, is start filling them up. The dry coolers you mentioned are inevitable part of it, too. So turning on some of these would easily get us your mentioned hashrate. I hope we will finally see some AM hashrate's rise soon.
You're right. It was not containers, it was probably HK datacenter.
Lets assume that AM have 2 rows with 10 racks as picture shows. That give us 60 small-bath-containers (3 for each rack as on picture). Lets assume ~300 Th in 60 "small containers", so its 5Th for one.
On the other photos we see that each "small container" is filled with some ... "big blades" with 92 gen1 blades, so it gives us ~1Th per big blade, how many of them are in one "small bath container", 6? So now we have 6Th per small container, 18Th per rack and around 360Th for two "fully populated rows".
The last mentioned batch for gen1 was 500Th, so 300Th for HK datacenter and 200Th for 4 containers(4x50Th) seems right, the question is, where are they mining right now?