After living through the covid and vaccine scam there aren't too many conspiracy theories I'm not considering . However flat earth is NOT one of them.
I have been an amateur radio operator for 55 years. I have talked all over the country and outside the country on short wave (below 30 Mc) radio. Shortwave radio can go long distances because the radio waves bounce off of the ionosphere. However, at higher frequencies, above the maximum usable frequency, which varies depending on the time of day and the 11 year sunspot cycle, the radio waves do not bounce off of the ionosphere but go right through it. Also at higher frequencies the radio waves do not bend. They may refract a little but they do not bend. Therefore at the higher frequencies, because of the curvature of the earth, radio transmission is limited to line of sight. That is why TV and FM stations put their antennas as high as possible so that the radio waves can see more of the earth. That is why an FM station (FM stations are 88-108 Mc) can use the same frequency as a station 200 miles away and they don't interfere with each other. On the much lower frequencies of AM radio (500-1600 KC) radio waves bend a little around the curvature of the earth but not much but they only bounce off of the ionosphere at night. That is why many local AM stations are required to shut down at sunset and only a few of the big ones are allowed to operate 24 hours. Otherwise they would interfere with each other. If the earth were flat none of this would be so. FM stations and daytime am stations, operating on the same frequency, would interfere with each other. No matter how much power an FM station runs it cannot go more than 50 miles or so unless it has a really tall antenna.
Also I know the people who run the King of Kings radio network (kingofkingsradio.com) in KY. They have 8 stations throughout KY, TN and Ohio. They are linked by satellite dishes. Also an Amateur radio association (The ARRL) has launched several Oscar satellites since the 60s. thousands of amateur radio operators have worked through these satellites by pointing their antennas toward the sky for many decades. So I know satellites are real and orbit the earth.