Q: Shouldn't the sun get blurrier if it is being magnified?
A: The sun actually does get a bit fuzzier when it is at the horizon compared to overhead at noonday.
Q: Shouldn't polarized sun glasses or a welding mask be able to restore the sun to its actual state?
A: The explanation is describing a projection upon the atmoplane. The projection is appearing upon a medium between the source and the observer. Polarized sun glasses or welding masks are useful for reducing internal glare lens effects within the eye; but would only darken the scene in this external situation.
It's handy they've provided answers, but they're completely nonsensical. For a start, "a bit fuzzier" is a HUGE stretch from "a tiny point of light somehow becomes the same size disc as it was at noon, with MINIMUM, 1% or less blurring effect".
What is a "projection upon the atmolayer" ?? A projection requires focus on to an image plane. Light through gas is not focusing on anything: light rays are scattering, not converging. It's interesting they give a laser as an example: further proves the RE point. A laser from 1cm shows a single point... a laser diverging at 10m shows a bigger "point", and A LOT fuzzier, when projected on to, say, a wall... there's no "focus" to it at all. It's not as if it's focused for 9cm then fuzzy for the remaining 1cm... it's completely fuzzy.
If you point a laser directly at someone 10m away, they will see the single point in the middle...(or more to the point, they will get a single point burnt in t otheir retina!) they may notice a slight "haze" surrounding it but the majority of the light they see is from the centre point. Try the same with your phone: torn the torch on, hold your phone a meer 5cm from the wall and it projects a pretty huge circle even at that distance: close to 5cm wide on my S8 anyway! Now the hold the phone pointing the torch towards you... 5cm, 10cm, hell even 30cm away from you: do you see a giant 30cm disc of glowing light?? No: you see a very bright spot coming from where the torch is. Their laser light is example is beside the point: obviously the lamps in the photos are illuminate a much larger area than the "orb" of light you can see in the photo, so the laser light example is irrelevant.
Hold your phone in front of your face with welding glasses: because the centre of the light, the light source, is the brightest point, regardless of all the scattering that occurs, the brightest point by far is still the light source. This is where the greatest concentration of light rays, with the greatest intensity, are coming directly towards your eye. The "orb" of light emanating from the torch, is no longer visible, only the light source, and it's true size. Perhaps I need to demonstrate this with photography. It's quite easy to do: just use faster shutter times or smaller apertures.
Perhaps this argument can be won by simply sending flat earthers pairs of welding glasses?