Scott Townsend wrote:

We have one of those Hot water Taps at the Kitchen Sink, heats up the water
on a separate spigot. It is NOT a Point Of Use Instant Hot Hot water heater.

When we use it (since we bought the house, so 4 years now) there is a
somewhat sweet smell that comes from the water that comes out of it.

Does not seem to have a taste. Though we mostly use it for preheated water
for boiling, or cleaning....

I have not crawled under the sink to see who makes it..

Scott-

Crawl under the sink and find the manufacturer and model. Lookup online
for a manual and see if there is a periodic sanitizing procedure for it.
Draw samples of the water from that tap and from a regular faucet and
have them analyzed.