Galaxy s20 fe. New phone. Tried ALL the suggestions to get that notification connected to call settings to turn off. Nothing worked. The sliders in call settings are grayed, can't turn anything off. Current update had no change there. Wonder who at samsung decided we needed that constantly showing, when mobile data isn't used continuously. Otherwise, I enjoy samsung products.
That is not the case, I have not had this issue with my 20FE, that is more than likely a bug. I would say back up your data, factory reset your phone, verify the issue goes away, and after restoring the back up, if the problem reappears, than it's more than likely a setting that was changed. Hope that helps!