From new my 2018 F3L had terrible FM reception. I took off the antenna and found the normal thread locker on the threads. Cleaned all that off the antenna and chased the mount threads. There was no improvement. There was some plastic mold flash on the antenna mating surface of the mount. Cut that off and filed it flat. No improvement. Took apart the antenna cable at all the connectors and inspected them. No problems found. So at my first service. I always get my first service at the dealer. I told them about the issue. They agreed there was a problem, but was not able to improve things.
So earlier this year I installed a camera system. As part of that I took off the top case. When I took off the antenna ground strap. The bolt was covered in thread locker. So much so that some came off the bolt and was between the ground strap and the frame. During reassembly. Cleaned all the tread locker off the bolt. Chased the threads on the bolt and frame. Cleaned the the thread locker off the ground strap. Reassembled. The FM reception was greatly improved. It is now useable but still think it should be better.
That is something else you can check if your FM reception is not very good.
