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I have the icon in my quick settings panel on my Note 20 Ultra. Did you check the menu of the quick settings panel to see if the icon is hidden? When you open the quick setting panel, swipe down again to access all of the buttons, the menu option is on the right side (the 3 dots) next to the system setting icon. then click on button order and see if the mobile data icon is there, you can drag it down to where you want it.
Did you check if the icon is on page 2 of the quick panel? You can swipe left to see the 2nd page.
If you don't find it there, click the 3 dot menu and select Button order. Across the top it will show icons that you can drag down into your quick panel. If you swipe that list left you will see additional ones which can be added.