Some text in "outline" style and no way to change it?

Some of my text in Editor suddenly shows up as outline only (ie. not filled). I’ve not made it so and there seems to be no way to modify that effect at all.

Image 1 for reference.

All the text should be similar to the topmost black text (only color should change), but somehow both the red and the black text that follows are in “outline” mode.

How can I change to so all the text is just normal without any other effects than color?

Use the View → Text Editing → Show Invisibles command to see if there are tabs or other hidden formatting associated with the problem text.