Tested in build 3.4-SNAPSHOT-705 (spigot)
the portal block is not shown correctly:

in-game:

texture.png

Ditto. The dynmap texture is far sexier and far more striking, and its unlikely to appear for most users maps.

Mike, please do consider the 'wont fix' tag for this 😜

Yep - I'm actually having difficulty FINDING where that texture comes from: not sure if it is a texture resource, or a code generated texture :). I used what I used because there WAS a texture for it (it's the 'end_sky' texture, which is an environment texture vs a block texture :) ).

Checking out some resource pack forums, it looks like the sky texture is reused for the portal, but "It is recolored per-layer, (meaning the hues you see in-game is put there by the game"

unless a better representation is suggested, closing up and will add to our minilist

I'm a fan of the texture Dynmap uses for what it's worth