Some of us have kettles , even in the benighted medieval dystopia of the US, but we think of ramen as food, not something where you just add hot water.

That's crazy, I've never heard that. I know our hot water heaters are kept high enough that bacteria can't grow, and every source I've found says the other risk is lead contamination, and we don't have any lead pipes in our house, so I'm going to assume this is an old outdated rule. Plus for the bacteria concern, it's being boiled again anyway.

I thinks it’s more lead )and other metal) accumulation but yeah …..

The first time I remember hearing a specific , not generic, concern was when legionnaires became A thing several decades ago. People were turning down their water temperature to save money. But legionnaires is more tolerant of heat than most other germs, so there’s a window of opportunity where the water is hot enough to kill off most diseases but cool enough to let legionnaires flourish.

Even today, you’re supposed to keep hot water at 120°F at the tap to prevent scalding but your water heater at 140°F to kill off legionnaires. Most people dont

Well yeah, but if u put it into a kettle and boil it, it should be fine, cos boiling kills the bacteria.