I noticed three side-by-side rectangles on the map in my game. Disabling the Vehicle Wagon 2 mod makes them vanish, so I assume this is what causes them?
The shapes are half-transparent, the middle one has a red tint, the outer ones yellow. They don't align with the grid completely, but their size is roughly 4×4 and 4×5 tiles, respectively.

I can provide an in-game picture as well as a save if needed.

A picture would certainly help with a graphical issue.... Sharing your save file would be even better.

Sounds like the visualizations that are supposed to appear when you click on a wagon with a winch to unload it. Those are supposed to be visible only to the player who made it, and deleted when the player clears the winch from their cursor. Not sure they should be on the map at all.

The colours indeed match the ones displayed when using a winch, though they are more opaque.
Sure I'll hand in the files. Where/How do you want them?

Any file share, like google drive.

Here you go:

• image:
  https://drive.google.com/file/d/1B7A_1Wi4fK-oTch533CMAfVW3Ujij6xd/view?usp=sharing

• savegame:
  https://drive.google.com/file/d/1gxi_nyTJtNeP-CNq3UkXnLc6XXYuULw-/view?usp=sharing

It's near the map centre. I marked the position on the minimap with an info symbol ("Weird rectangles are here [virtual-signal=signal-yellow][virtual-signal=signal-red][virtual-signal=signal-yellow]")

Thank you very much for the report. There is a bug in the autoloading code that is rendering selection graphics at the map origin because the order was not given by a valid player. I will fix it for the next release (4.1.10) and delete all the extra rendering objects. (This could have turned into quite a bad memory leak if it went unnoticed for a long time.)

This should be fixed in 4.1.10. Colored squares in existing saves should be deleted during migration when the save file is loaded.

Updated my game. Yep, the shapes are gone. Thank you a lot!