Additional shut off valve, below sink or in basement. Incomplete pipes not tied into bathroom sink line.
You have a particle stoppage down stream or poor venting
A typical bathroom sink uses around 1.5 to 2.5 gallons of water per minute when the faucet is running.
Snake your drains
The mesh filter at the head of the faucet is clogged. Take it off, clean thoroughly and re-install.
A poor plumbing job. The pipes to the shower & sink share a pipe to the water heater and the pipe is not large enough. This causes the water pressure in the pipe to drop when the hot water is turned on at the sink while the shower is also on.
Unscrew the aerator from the end of the faucet where the water comes out and clean the screen. Sediment build up slows the flow.
Replace the faucet.
Check the shut-off valve for the hot water side that's under the sink and make sure it's fully open.BECAUSEThe installer did NOT remove the aerator prior to the installation and the flow restrictor is blocked
The most likely reason is that the hot water valve is turned off in the bathrooms. Look under the bathroom sink. There should be two valves - the one on the right controls the flow of cold water and the one on the left controls the flow of hot water. Turn the hot water valve counter-clockwise to open.
I would try it on a small spot to be sure but most hotels do this.
An average bathroom sink is 6-7 litres