I’m not sure the real use case for immersion cooling in hpc. Cray2 and T90 used that technology, but they consumed hundreds of kilowatts, but spread across thousands of surface-mount gate-arrays on dozens of boards. The wattage per total unit volume was very high, but not concentrated point-loads. As such, putting individual liquid cooling blocks on components was impractical.
For a modern hpc server immersion cooling would put the coolant right in contact with the component, rather than across a copper water-block, saving a degree or two of delta-T, but at a very high cost with regards to reliability, maintainability, weighs a lot, and often hurts space efficiency, as all parts have to be extracted from a tank vertically.

https://www.sandia.gov/portals/history/