On Minecraft 20w18a, I removed and replaced some maps in a desert village that I live in due to the way the text is rendering on the map as dark gray rather than white like the banner markers originally were.

When the maps updated the area around me, it "tore" through the map as shown below. The location of this specific map and where I updated the map from was on the point facing south.

I do not recall this being an issue in 20w17a but I could have very well just not noticed it then. As noted, the names cut off between maps as if they are player names that are crouched, they are grayed out as if they are player names that are crouched, and the map rendering has torn entirely and surveying the area showed that this is not what the area should look like on the map.