I assume that it's not the HDMI output from the Pi that produces this kind of interference but rather the monitor itself.
Though it's entirely possible that Pi leaks HDMI into the ether. Someone with a Pi4 and a RTL-SDR could easily verify it: pixel clock frequency of a 1024x768 signal is around 50 MHz.
Though it's entirely possible that Pi leaks HDMI into the ether. Someone with a Pi4 and a RTL-SDR could easily verify it: pixel clock frequency of a 1024x768 signal is around 50 MHz.