Clearing formatting results in different background color for different renderers

VS Code issue: https://github.com/microsoft/vscode/issues/160497

![image](https://user-images.githubusercontent.com/2193314/190413547-2a7fa930-7784-4f8c-870d-36a059d35e58.png)

The rendering of the repro in the linked issue is different in webgl+canvas vs dom