EF 24-70mm II is not stellar; that is just a fact of life even if you have a perfect copy that probably hardly exist. The big yugge problem is insane field curvature meaning that you just can't get sharp picture at infinity from corner to corner but you can knock yourself out shooting narrow street architecture and magically it is in focus when it should require focus stacking. They are not so bad for lifestyle but again critical sharpness wide open is nowhere near as good as say 50mm ART. Passable on R6, not beyond. 35mm was particularly weak if I remember correctly. The good parts include great flare- and ghost resistance and reasonably low vignetting by today's Canon standards.
I happily got rid of mine. I have 70mm as 70mm ART macro or 70-200mm, I have 35mm tamron or 16-35mm zoom, and 50mm ART for in between. In over 2 years I never regretted selling it and not getting a replacement.
Problem with RF 28-70mm is the fact it is budget optic (think Tamron 28-78mm f/2.8 III which is most likely much better), but costs like a premium one. Then we have a wild distortion, some sharpness issues here or there . That STM motor... I really don't like them. Do you enjoy how your 50mm focuses? I'm guessing not...
Is the Canon RF 28-70mm F2.8 IS STM Lens right for you? Learn all you need to know in The-Digital-Picture.com's review!
www.the-digital-picture.com
Review of this more "budget-oriented" fast standard zoom lens for Canon R cameras.
opticallimits.com
No options are actually inspiring on Canon here, even if you have The money. A few primes is at least going to give you nice sharp images with plenty more DOF control and available light.