Yeah, I was in the same boat for a while. After seeing what @the_drew said about towers cooking older phones, I actually tried it myself with my backup 4G phone near a busy intersection. Same exact heating issue when the signal was weak. Makes you realize how much of the fear is just not knowing how the tech actually works.
My buddy Mark in Denver kept blaming 5G for his phone heating up near the cell tower on Colfax. He was using a three year old phone with a cracked screen. Then he borrowed his wife's older 4G only phone for a day and the same exact thing happened near that tower. He said it was a real duh moment realizing he'd been scared of nothing. Felt pretty silly after that.
Why do we always blame the newest thing first? Phones heat up when they struggle to get a signal, no matter if it's 4G or 5G. That tower was probably just in a tough spot for reception. It's wild how a simple test with an old phone can shut down a whole fear. Shows we should check the basics before believing the scary stories.