ReplaceBlobsFeature, the feature used to generate blobs of basalt and blackstone in the Basalt Deltas biome, underwent a breaking change in 1.16.2. In 1.16.1, the size of the X, Y, and Z dimension of the blob was randomized seperately, making a differently shaped blob each time. In 1.16.2, each dimension of the blob is the same, leading every blob to have the same spikey look.