Many 800V vehicles have a split pack that can charge in parallel at 400V or series at 800V so they don't charge extremely slowly at 400V. Those are fine.
Not so fine if you go by Silverado EV experiences where they fail to ever go into 800V mode reliably and cause months of dealership woes with zero fixes. [1]
In my opinion its just another failure point that makes me prefer 400V EV's.
