Old nether although there's a nether update?

I've had my Minecraft map for a long time, I haven't used any cheats there yet. Now I would like to know why my nether stayed the same even though I did the update. I play on ps4.

Because the update can only be applied to new maps or newly generated sections of an existing map.

I'm assuming that the current Nether is only loaded on new maps as otherwise it would be necessary to delete the entire Nether in your world and repack it. I'm not quite sure because I'm a PC player.

Because this does not overwrite an already generated area.

You have to explore new terrain where you have never been - then you will find the new Nether.

If you have a world that was created in previous versions, the new biomes can of course only be created in newly generated chunks.

Otherwise, all of your structures and locations can be destroyed, since the game can't distinguish what you wanted to keep