Nvidia's automotive and aerospace variants get ratings up to 85C, for comparison.

Don’t their consumer GPUs run at 85C core temp? Maybe not for as long though.

AMD CPUs basically all boost up to 90°C as a relatively normal operating temperature as long as the power (and some other factors) allow it to. I assume AMDs and NVs GPUs do to, but I play mostly CPU bound games so I see mine just sitting at ~60°C under load.

Core temp though. Ambient temp is a different story, and also depends on air vs water. In fact the article suggests the difference is getting the water more directly onto the chips, no mention of running at a higher core temp.

Temperature ratings are the allowed ambient temperature. The actual silicon will inevitably operate somewhat higher, because coolers are just moving heat down a temperature gradient.