New Maps in snapshots

In any chunk generated in an old snapshot ( maybe even older by a week or two ), opening a new empty map. just to clarify In newely generated area's its fixed.

What I expected to happen was...:

After opening the new map it should show a regular old map.

What actually happened was...:
1. The map is showing random lines (of caves i persume), they can be removed by building above them and therefore ubdating the map (after removing the blocks the random line is gone).

2. Showing lava and water spots that are not representing lava and water on the surface but actually representing flowing lava or water under ground.

Steps to Reproduce:
1. make an world in an older snapshot.
2. go to the newest snapshot version (20w22a)
3. make an map