Important distinction to avoid confusion: Tesla ended the CPO program about a year ago. What you're talking about is a used car and not a CPO which would normally denote a certain level of cosmetic inspection and refurbishment. What you're getting is a used car with a factory warranty against mechanical defects that likely hasn't even had the 70-point inspection done that they claim. It's important that you know you're buying a used car and inspect it thoroughly as any cosmetic issues are yours once you sign the paperwork. If you want them to fix anything ask before you sign paperwork and force them to put it in writing.
That aside, there's normally a rubber mat that goes there. They may have removed it to install/remove a phone charger and not replaced it. You can ask Tesla for a charger part for your phone or a part to cover it but if you've already taken delivery they may not be as willing to give you freebies as they would had you made it a contingency before taking delivery & getting that in writing. You're now beholden to the mood/whims of a service writer so the outcome is unknown with zero consistency any direction surrounding similar situations to predict the outcome.