The claim that HAARP is responsible for the aurora seen worldwide on May 10, 2024 is false. The phenomena was actually caused by a severe geomagnetic storm triggered by a series of powerful solar flares and eruptions from the sun. Since the aurora borealis (or northern lights) are caused when "charged particles ejected from the sun during solar storms collide with Earth’s magnetic field," this unusual solar activity led to the lights being observable in many more places than they usually are. The article below cites the National Oceanic and Atmospheric Administration’s Space Weather Prediction Center (SWPC).
https://www.earth.com/news/auroras-southern-united-states-this-week-huge-solar-storm/
In addition, it's important to note that the Alaska-based HAARP, or the High-frequency Active Auroral Research Program, is often the subject of unsubstantiated conspiracy theories. Common misconceptions include the claim that HAARP can control the weather or manipulate brainwaves. In reality, the function of HAARP is to "heat small regions of the ionosphere and observe the effects" for the purpose of scientific research, according to the University of Alaska Fairbanks.
https://www.uaf.edu/news/archives/news-archives-2010-2021/haarp-research-attracts-conspiracies-misunderstandings.php