Just checked (ST 4.0.5, 9th Gen iPad iOS 26.3) and what I'm seeing is a consistent 4 lines of text being left between the top of the lyric pane and the highlighted lyric line. My device is set at default font size and modifier.
Now, this does change if you start changing the Size Modifier (https://stagetraxx.com/docs/v4/settings/general/lyrics-chords-pdf/#size-modifier) setting. If you increase the size modifier (i.e. text gets larger) then the number of lines between top of pane and highlighted line is reduced.
Will wait for @peter to comment but the way it is operating may be intentional to factor in people changing to larger fonts. If this is the case, I guess there is still a point to be made of 'top alignment' being 'top' irrespective of any font size or scaling changes.