Yes I have seen a similar graphic before. I think it is absurd and does not work. Just to point out one problem with that graphic, if that were true then when the sun was at sunrise or sunset it wouldn't look like the sun was going down or up as it does, it would look like the sun is going sideways because of the curvature of the flat earth and the curve of the sun's movement. Also if the sun never really went down below the earth you would be able to see it always because there is nothing blocking the rays of the sun. If there is nothing between the sun and us, as on the flat earth model, then the rays should always reach us.
Maybe I am mistaken but I cannot get it to work in my mind.
Happy Christmas. Thanks for asking honest questions and treating us with respect.
There is no obligation to believe as a flat earth that the sun and moon are flat discs. They could be spheres.
Just skip to the pictures which explain well, rather than watch, but this video has some good images which explain how the law of perspective works.
Check out the one with the dog and the boat.
If the sun was a sphere you objection would be better answered. There are also possible atmospheric conditions to be taken into account as the sun clearly changes in size.
The law of perspective does answer your question about the rays never going away when you reflect about it.
Another thing to say, is that if it is just to difficult, remember that modern astronomy makes us think we have the answer to everything and can see much further than we can. Now all of that is based on a faulty premise.
If you are still not convinced, then just focus on the curvature issue. The most scientific and irrefutable part of the flat earth which makes all the rest of the modern system fall to pieces.