Cherry did that with their (vintage) programmable Cherry G80-2100:
At least mine has normal (vintage) Cherry MX Blacks, but three keys, especially those which switch to programming mode or change the layer of the 24 programmable keys, had much heavier springs (IIRC around 150g) in there — and you really don’t press them accidentally, even though they’re left and right of the “up” cursor key. Some people call those switches Cherry MX Superblack.
The third MX Superblack switch is IIRC either under the Scroll Lock key or the Pause/Break key. No more sure under which of them.