I have a note 10 plus ,I always used superfast charging. no issues till date giving excellent battery backup. not sure about the s20 ,but using superfast charging will not be a problem for efficient battery life rather than it cause the wear and tear of the battery and decrease the battery capacity, but that will take 2 or more years.
accept solution will be appreciated if my post helps you 😊
From my personal experience I have always seen that whenever I charge my phone slowly it gives better battery life. Although on a daily basis I use fast charge/super fast charge whichever charges faster.