Only rarely and partially wrongly generated biomes in the Nether in the 20w18a

Until 20w16a, the new Nether biomes were always generated in large numbers and area-wide. In 20w18a, no only very rarely biomes were generated in the entire area in the same test world. Partially the bioms are not there because there are only big lava lakes at that place.

Nether fortresses and bastions seem to have been generated in 20w18a at the same locations as in 20w16a.

In newly generated worlds I could also only discover distant and isolated basalt delta biomes.

Seed: 8448929408712390508, all settings to normal/default.