The Nether is no longer on the web map at all. Its Safe Zone was real and the register still keeps an account of it - there was simply no reason to publish a picture of it, and the picture was misleading.
Whether a dimension is charted and whether it is drawn are two questions now. They were one setting, which meant taking a map off the website would have made that whole dimension lawless.
Nothing about where the register goes quiet has moved. Your client will connect exactly as it did.
The full list of changes
01One border, many lines
Minecraft keeps a single world border and applies it to every dimension - setting it in the Nether sets it in the Overworld, which was measured on the live server rather than taken on trust.
The line between the two halves of the world is not one number, though: in the Nether it is written in the Nether's own coordinates, an eighth of the size. Drawn out to the border, the dark half there was sixteen times too wide and the safe half a stamp in the middle of it. The fix is that the red reaches as far past the line as the safe half is wide, in any dimension, which needs no number written for it.
And then the Nether map came off the site entirely, so on this world you will not see either version. The fix stands for any dimension that is drawn, including one a mod adds later.
Taking it off needed a second setting rather than the one that was there. The one that was there decides whether the register keeps an account of a dimension at all, and answering it with a no to remove a map would have made the Nether lawless - no claims, no tolls, no case before a bench. It kept all of that and lost only the picture.