The R6 Mark II doesn't have the smart controller, whereas this rumour suggests that the R5 Mark II will.
If the rumour is true, then I would bet Canon will make two new grips -- an updated grip for the R6 Mark II, and a new grip for R5 Mark II with smart controller. Otherwise, it would be odd for Canon to make a dual compatible grip again when one camera doesn't have the smart controller built in for the landscape orientation.
EDIT: When the R5 came out in 2020, I had just sold my 1DX Mark II. I love the integrated grips of the 1D-series bodies, so I immediately bought the BG-R10 for the R5 to feel more "at home" with the new camera. Unfortunately, adding the grip was not nearly as comfortable or as pleasing to use as the integrated grip of the 1DX. Canon placed the joystick in a really uncomfortable position, and I often found myself searching for it with my thumb. If Canon is bringing out a new grip, or grips, I hope they tweak the design a bit in this regard.