Minecraft wiki entry for Development_versions, associated text: MC-176491 – Nylium randomly catches fire from lava, and burns infinitely.
MC-187357 – Strongholds will not generate in floating_islands or caves preset.
MC-189736 – distance within a predicate no longer works.
MC-190552 – Demo mode resets position and inventory upon launch.
MC-190859 – floating_islands or caves buffet worlds no longer generate strongholds, and ender eyes do not locate previously-generated strongholds after upgrading to 1.16.