VSCode version: 1.49.2
Theme used: "Default Dark+" with some color customizations
Specific relevant settings:

"editor.renderWhitespace": "trailing",
"workbench.colorCustomizations": {
    "editorWhitespace.foreground": "#FF0000"
}

I've enabled the recently added "trailing" whitespace rendering option, and set the foreground colour to make any trailing whitespace stand out clearly. That works fine. I like the new configuration option, thanks!

Since changing the whitespace foreground colour, I have noticed that whitespace rendering is applied in the SCM commit message box when text is selected. For example:

As can be seen, some kind of rendering or overlay is being applied to spaces in the middle line, making it very difficult to read. I have confirmed by experiment that the "editorWhitespace.foreground" color is being used. When a less obtrusive color was used (as per the default, and a typical choice when all whitespace is rendered), the impact was less noticeable.

I don't think that any whitespace rendering should be being applied in this box at all. If some users do desire it, I would expect them to want it at all times, not only for selected text.

I attempted to track down a location in the code where the rendering and associated color settings are applied for a SourceControlInputBox and thus be able to make a PR, however I don't have any knowledge of js/ts and it was taking me a lot longer than is reasonable.