This unit is direct wired. Going to be interesting to see if it is charger wiring, charger defect, charger setting, or truck issue...
I am going to try this unit (as recommended by @omamatt): SnapPlate 2021-2022 Rivian R1T & R1S Removable License Plate Mount . Not cheap, but should do the trick.Congrats on the purchase.
California requires a front plate too. I live dangerously without it. Generally something they'll only hassle you about if you get pulled over for another reason. Even then, it's just a fix-it ticket. Your call if you want to install it.
Would recommend just using some 3M double-sided tape, instead of putting permanent holes in the front end. That stuff sticks extremely well, but can be removed if so desired at a later date.