Environment

Windows build number: Microsoft Windows [Version 10.0.18363.720]
Windows Terminal version (if applicable): 0.10.781.0

Any other software? A preview version of PS7 which displays a "new release is available banner"

Steps to reproduce

1. Configure PS 7 preview shell as the default profile
2. Launch WT
3. Snap terminal left immediately after launch as soon as WT is visible. I suspect it needs to get snapped while the banner is being drawn before the shell is ready for input.
4. See background color from the PS 7 new release banner is used for the entire terminals background color
5. As new text is drawn to the window the background color starts to go away and correct itself.

I saw this behavior by off change. After it happened once I was able to repo after a dozen or so launches.

Expected behavior

1. The background color used by the new release banner should not be drawn over the entire terminal window.

Actual behavior

1. Banner background is used as the terminal background color

First time it happened:

Second time it happened: