Slashed Chunks

So, I had this world in 1.16.5 that I used the datapack for Experimental Settings when I updated it to 1.17.1, but then, when I updated it once more to 1.18.1, there were this slashed chunks which I supposed were not going to be a thing, since the update fixed all of this things automatically. Is it because I used the Experimental Settings? Is there anyway to fix this problem?