Symbol lines and symbols ignore small staff size
Most things will change correspondingly if a staff is made "Small" in Staff Properties. Not so with lines, apparently. To reproduce, create a new score, add some notes, add a trill from the Articulations & Ornaments palette to one, and add a trill from the Lines palette to another. Secondary-click the staff, open Staff Properties, and check the "Small staff" checkbox. Result:
It should be noted that there is no workaround for this.