I believe this is equivalent to MCPE-23622 except for java edition instead of bedrock.  When the player is near the border of a map (exact size depends on map zoom level) the player icon shows as the round dot rather than the arrow even though the player is still within the extents of the map.  This means that for two adjacent maps there is a strip between them where the player icon is displayed as a dot on both maps.  The same thing occurs for other icons near the map border (at minimum banner icons and maps-in-item-frames are confirmed).  They are not shown on either adjacent map.

Steps to reproduce:

1. Create two adjacent maps at largest zoom level (larger maps have a larger bugged area, so it's easier to observe the bug).
2. Hold both maps and walk/fly from one to the other.
3. Observe that the player icon leaves the first map (becomes a dot) some distance before it enters the second map (becomes an arrow).  Expected behavior is that an arrow would always be visible on exactly one of the two maps.
4. While standing in the border area (icon is a dot on both maps), place a banner and right-click it with both maps.
5. Observe that the banner icon is not visible on either map.  Expected behavior is that a banner icon would be visible on exactly one of the two maps.
6. Place two item frames in the border area and create a "map wall" with the two maps.
7. Observe that neither map shows the green arrow icon that indicates a map in an item frame.  Expected behavior is that the green arrow icon would be visible on the "map wall".