From Ham Radio Workbench episode #250, around 2:23:00 mark.

They are talking about VHF, UHF, and microwave frequencies going beyond line-of-sight.
These are line-of-sight frequencies which do NOT bounce off the "ionosphere" according to their model.
These frequencies should TOTALLY, ABSOLUTELY go off into space rather than bounce around, according to their model.

But experienced hams point out that "not rarely" you get comms from Hawaii to California. Or other 600-700 km comms. That is WAY BEYOND LINE-OF-SIGHT.

They don't ever put 2 + 2 together, and start to question the Globe model they have been given since childhood.

It's not just "weird" or "one of those things" -- it DISPROVES THE MODEL. It FALSIFIES the model. Given the model we have been taught, the experimental results they speak about are LITERALLY NOT POSSIBLE.

You need to go back and question the model when you encounter evidence like this. AS A SCIENTIST.

You see, I was faced with this and similar evidence. But rather than suffer cognitive dissonance in silence, or willfully dismiss the truth because I didn't like it (or it made me uncomfortable), I looked into flat earth with an open mind. And guess what? Now I'm a "flat earther". I know, that's one of the only unforgivable beliefs these days, similar to r4cist or n4z|, but c'est la vie.

What about tropospheric ducting and sporadic E-skip?

https://3fs.net.au/tropospheric-ducting/

https://northpine.com/2020/06/18/tropo-or-e-skip-nows-the-time-to-listen-for-distant-fm-signals/

Neither of these propagation methods rely upon line of sight.

Many times during the year, I receive TV stations 300-400 miles away through tropospheric ducting.  (I have a high-performance antenna, the Televes DATBOSS that is designed both for low- and high-VHF as well as UHF.)  Sadly, though, with the sharp reduction in the number of TV stations broadcasting on low-VHF, viz. channels 2 through 6, E-skip is a fairly rare phenomenon these days.  Back in the analog days, I received stations from all across North America, and the beauty of it was, no specialized equipment was really needed.  I've picked up stations on E-skip with just a set of rabbit ears.

Also, in analog days, the picture was very often smeared or distorted, whereas with the advent of digital TV, you either have the signal or you don't, and a distant signal is just as clear as a local one.

There is also the phenomenon of knife-edge propagation, where you don't strictly have a line of sight, but the signal reflects off various terrestrial barriers such as ridges and mountains, and ricochets on past them.  I regularly get stations from 80 to 100 miles away using knife-edge propagation, and a handful of them are reliable enough for almost-daily reception.  With tropo and E-skip, it's just a chance phenomenon.  (Tropo can also combine with knife-edge for some very good results.)

Here's one example of an discussion about Marconi's experiment ...

Scientific discovery: At the time of Marconi's experiment, the existence of the ionosphere was not yet fully understood. The transmission was an empirical proof that radio waves could travel beyond the horizon, and scientists later worked to understand the principles of ionospheric reflection. The electrically conducting layer was first named the "E-Layer" by Sir Edward Appleton in 1927, derived from the name "electrical-layer".

You'll notice the embedded assumption, that the radio waves could travel beyond the "horizon" ... which assumes a ball earth horizon, 100% begging the question.  So then they had to figure out a way to explain this away but without touching the sacrosanct embedded assumption.