The world border looks glitched from outside(actually not really weird, details in screenshots)

How To Reproduce:

/worldborder center ~ ~

/worldborder set 250

note: do not set it too small, otherwise cannot see the difference.  

get an ender pearl and throw it outside the boarder.

look at the place where you can see two side of the border on the same angle, and that's where displays abnormal.

in the following pictures "border.bmp", I've shown where can be seen an where is the world border.

if the side that is furthest from you cannot be seen, then there is an angle that looks normal(that's why I mentioned set the size larger above.).

the abnormal display in some angle is:

on the near side of the border, it looks like one border texture shading the other, as the picture shown below.

this looks normal in the sky, but you can still see both texture of near side and the other side on the ground, that supposed to be can see only the near side.

————Updated 2021/02/01————

After several times of trying, I noticed that this effect has direction, which means when you are on the outside of southern side you can see this glitch happens on the side(like the picture I uploaded), when you're on the outside of northern side you can't see the glitch. on the outside of western side you can see the glitch on the opposite side, on the outside of eastern side you can see the glitch on all the side. On the corner you will see the two side has different effect.

P.S. this means the last picture I've uploaded has direction too, the left and right is north and south, the up and down is east and west. what I said that the eyesight affects this is in fact true, but this effect will mix with the effect I mentioned above.