Faucet runs slowly on hot, fine on cold
1 - Check that your valve under the sink is open, someone may have knocked it mostly shut.

2 - Or, it could be that debris finally got washed up into the hot water valve or sink supply hose under the sink or in the faucet. You'd turn off the valve under the sink &amp; disconnect the hose from the faucet, but not from the pipe &amp; hold the hose in a bucket while you turn the valve back on &amp; hopefully see the debris shoot into the bucket.

3 - If the flow is reduced in the existing hose. Then, you'll need to shut off the Main water supply valve to remove the sink pipe's valve &amp; hose. To then, put on a garden hose or bigger long hose to fit over or around the pipe &amp; clamp it down with a hose clamp or band clamp. Put the other end of the hose in the shower or tub, weight it down with something heavy &amp; go turn on the Main valve to flush the pipe clear &amp; hopefully find the debris in the shower or tub.

4 - Or, which is very common, that the hot water has deteriorated the hot side of the faucet's internal cartridge or seals &amp; springs. Call a Plumber to rebuild it or take it all apart (with pictures all along the way) &amp; match up what you need to a rebuild kit at the store, if you don't know what model it is.