So this happens when im entering an existing portal or two , in whichever one i do , the terrain around the current chunk or the square around me that im standing is the only one loaded , the rest chunks of the world around me / close to me dont load properly . Its that i have to fly towards the unloaded one's  to only load a bit  of them or something like that. Work around that i dont know what that is. In both the overworld and the nether that i've entered same stuff happens. Didnt try it with the end dimension though.HJJ