Water – Cold water only dribbling from faucet

Your kitchen hot water faucet probably requires replacement (or possibly repair). From your description it sounds like the hot water side has clogged up to the point that it is restricting the water flow. Most likely cause is heavy calcium deposit inside the faucet and/or the hot water piping leading to the kitchen sink.

You should disassemble the kitchen faucet and inspect the temp/flow control valve assembly for debris/obstructions. It is common for debris to get knocked loose and flow downstream, causing problems like this. Your manipulation of the pressure regulator could have done it.

Another consideration: those bathroom faucets appear to be older and may not be of the "water saving" variety. The kitchen faucet seems new/modern and likely has water saving flow restriction, either the sort described by @Ed Beal or integral to the design of the flow control valve.