When testing an upgrade to my server world, I noticed hard chunk borders in at least two locations, as shown in the attached screenshots.
-Create a new Large Biomes world in 22w14a using seed: -7657144403601288391
-Copy this Region folder into the new world directory:
-Travel or teleport to the locations shown in the screenshots.
-Observe harsh chunk border running north to south at each spot.
Using this method previously to upgrade the world from 1.17.1 to 1.18 yielded proper biome blending, as can be seen near spawn in this test version.