I do not see what you are seeing.Possible to take a screenshot when it happens?
It's an icon to indicate that Control Center can be accessed from that location. Some discussions of it in various different threads, including a fairly recent one at https://forums.macrumors.com/threads/how-can-i-hide-this.2114999/On the X where you drag down to see the battery percentage it I have seen where it shows too dots in an oval that looks like on/off buttons and it appears and goes away.
What do that/those icons mean?
https://forums.macrumors.com/threads/how-can-i-hide-this.2114999/#post-25982128So just a visual reminder that Control Center is there?
(If so thanks for the clarification.) Anyway to disable?