Words that are underlined sometimes have a slight space added to the beginning. It happens, for example, with the letter “s”, but not the letter “b”. I didn’t go through all 26 but it seems it only happens with rounded letters like a,g,s,o, and e, and uppercase A.
Using the arrow keys to navigate to one of these words causes the underline and space to go away, which can cause the paragraph to jump between spanning the next line and reflowing the text all around it.