“Stellar activity and plasma turbulence near a transmitting planet can broaden an otherwise ultra-narrow signal, spreading its power across more frequencies and making it more difficult to detect in traditional narrowband searches.”
Science paper: https://iopscience.iop.org/article/10.3847/1538-4357/ae3d33
Review article: https://www.theregister.com/2026/03/10/seti_admits_its_search_for/
Broadening of specral lines info: http://www.hyperphysics.phy-astr.gsu.edu/hbase/Atomic/broaden.html
They do factor all that in to their thinking and also look for things like pulsed lasers. They’re not idiots like.