When connecting a red or green wire between two power poles, the target power pole will highlight if it's the same type as the source pole, but it won't if it's a different type. Illustration:
Small to small:
Small to medium:
Clicking it will still connect the cable though, so it's a very minor issue:
This is the same for each different type of pole/substation combination.
I don't have OCD, I have CDO. It's the same, but with the letters in the correct order.
I call this a normal bug, not game breaking, but it is, as the indication of the selection box shows if the entity is proper for the connection or not.
But yes, I like that the attention to detail is appreciated