Hello, sorry for the delayed response.
It looks like your message header is pulling paletteColor1 which is not ideal. Palette color 1 is typically used for content background. Go to Style properties -> Messages -> Message header, you need to define a better color here. This will set it for the light/dark style, by default because you're using a dark background for header on the light and dark style, you might be better off using a specific color like
hsl(222, 0%, 96%)
Let me know if that helps.