I deleted the data where the explored regions are stored and kept my progress, then I updated the world to version 1.18 and went to look for the portal at the end, but when I entered, I saw that the portal and the dragon were not generated.

Portal to go to the end /tp 1075.700 -33 1147.471

But when I recreate the same world, the dragon and the portal are generated.

Here is a copy of my World I cleaned before upgrading to 1.18 and 1.18.1-pre1