Maps in Java Edition still have only one color for grass, dirt, water, and leaves. This makes them useless for distinguishing similar biomes and is deeply unsatisfying.
Comments 3
This bug should be reopened. In previous versions maps had different colors for different depths of water, grass in different biomes, etc.
It's not clear if this is an intentional feature change or unintentional but I'm guessing the later. That means it is a bug. After all, why would they remove several useful map features without adding that to any changelog?
Again, this should be reopened since the behavior was in previous versions and the change was not communicated to players so we must assume it is a bug unless told otherwise.
Minecraft Suggestions post: https://feedback.minecraft.net/hc/en-us/community/posts/360023635552--Bedrock-Parity-Map-color-palette
Use feedback.minecraft.net for feature/parity requests