Because it's an obvious psyop that took over almost every social media platform. No one was talking about nuclear then BOOM everyone was talking about nuclear all of a sudden with exactly zero mainstream public input from politicians or even marketing from nuclear power companies. People hate nuclear, because some of us have been alive long enough to remember Three Mile Island, Chernobyl, and Fukushima (the worst nuclear disaster in human history, 2011).

Here's a list of every single nuclear meltdown/disaster/catastrophe https://en.wikipedia.org/wiki/Nuclear_and_radiation_accidents_and_incidents

The fission reaction to boil the water to spin the turbines is clean, but literally every single other facet of nuclear production, from mining, to enriching, to transport, to post-reaction storage (where nuclear waste inevitably always leaks) is disastrous for the environment.