So if they all burned up today it would be around a 6% yearly increase, globally? (1663 / 5200 * 5). And that's probably the most forgiving estimate I could come up with, I think your ~20% number is more accurate for future projection purposes given most of the mass was launched in a much shorter timespan.
Then the real question is what effect does space dust have on the earth's atmosphere (if any).
[1] https://en.wikipedia.org/w/index.php?title=List_of_Starlink_...