His perk is supposed to give a 20% increase in headshot VATS accuracy but after getting the perk, I get a flat 95% on everything, no matter how far away. It could list 1% for every other part and then 95% for the head.

This means that anything I can target with VATS I can instantly kill it, no matter how far away it is. If it's a 1% chance for other body parts, the perk should make it 21% but it's always 95%.

This has made the game trivially easy even on Survivor difficulty.

This is a confirmed bug. They probably know about it.