Above is a screenshot of the bug. See the mixed colors in minimap. I saw at least two other reports of this bug, but no comment that this has been noticed by the devs or is being tracked. Here is one.
Like the title says, this starts the moment you start switching views to other players. The color of the player that’s showing on the panel where you switch view never changes when you switch to another player, so all units and building they make from that moment will take the bugged color.
So let’s say the color of the player the replay automatically begins the view on is BLUE, when you switch view to the other player, the panel for switching view will still show the color for this other player as BLUE (this is a bug). Then all units and buildings produced by the player from then onwards will also show as blue on the minimap, and also when they go behind an obstacle, like trees, but are still visible (partial transparency of obstacles).
I hope I explained what I noticed is the main issue in this bug, and I hope the devs also track this.