[Gameplay?] Chat window keeps moving itself at the start of the game

I play with my minimap on the left side and my UI shrunken down. When I started doing this, I found that if you press enter (so you can type), then drag the blue bar at the top of the chat box, you can re-position the box wherever you want. It would also save those changes, so you did it once and it would be like that until you changed it again.

Since 4.18, I've had to drag it every time the game starts.

Steps to reproduce

1. Start a game, and move the chat box
2. Exit the game
3. Start another game and see if the chat box is in the same place as it was after you moved it.