Swamp floors (sand patches) do not blend properly in chunks generated in 1.13 or earlier

Upon loading some old chunks from 1.6.4, the floor of the ocean does not blend like it should. The block palate has a harsh change from the legacy sand/dirt/clay to solid gravel or mostly solid dirt in the case of the swamps. It is very noticeable and will impact any chunk that uses the legacy block palate which I believe includes versions up to the update aquatic (1.13).  Screenshots of the results are included.