You won't notice it on a single-word card, but once an explanation or example runs to two or three lines, the default line height makes the lines feel like they're touching. During review that's exactly the kind of thing that causes your eyes to lose their place and re-read the same line twice.
Try raising line height to 1.5–1.7. Sentences separate cleanly line by line, and even a long explanation becomes much easier to skim.
In ankieditor, click the part of the card you want to change to select it (clicking empty space targets the whole card instead), then adjust the Line height field under Text Style — either the slider or the number box next to it. Watch the preview update live as you dial it in.
Push past 2.0, though, and sentences start to feel scattered rather than read as a single block. Since this value is a multiplier on font size, it's also handy that the ratio holds even if you later change the font size.