Limitations of human visual perspective, quite simply. There's a "vanishing point" at roughly 3-5 miles, weather conditions dependent. We simply can't see any further than this when at sea level.

There are probably 1000+ videos you can find now by researchers that have taken their super-zoom Nikon P900/1000 cameras and demonstrated this over and over and over again. Boats, oil rigs, islands, etc. that are well beyond our visual limitations come right into view when zoomed into - and vanish when zoomed out (normal perspective). They've seen things 7, 10, 15, even 17 miles out to sea. And I might add, yes, they see the HULLS of boats as well. And to be clear, due to atmospheric conditions, there is always a limitation to seeing "forever", like trying to see something through 100+ plates of glass. Humidity, fog, evaporation, etc. eventually distort the ability to see things. You can think of this like seeing a mirage, which is atmospheric distortion.

If the heliocentric globe model were true, all of these things should be hidden by roughly 13-70 feet behind the curve.

There are so many videos of this, I'll let you pick the ones you like. Here are the best channels on YT to learn this stuff. Pick and choose as you're inspired:

https://www.youtube.com/channel/UClWTBNGnjXEZOtEwEp9BGTg/videos

https://www.youtube.com/c/DITRH/videos

https://www.youtube.com/c/jeranism/videos

The guy who runs the first two channels is offering 3 bitcoin for one single proof of the globe model. That's like $180K. Nobody has yet taken him up on it.