This is a (as of shortly after posting this) a feature you check toggle in the Focused Review panel. It is highly experimental, so I appreciate any feedback.
I suspect that the only real concern is that the schedule's review numbers might get thrown off, but I cannot see this change negatively affecting the mastery data, as it literally turns off the block of code that makes all the adjustments.
Awesome, thanks for adding this feature! Didn't notice any issues with it so far. One suggestion: It would be nice if there was a way to enable this by default, or the checkmark just remembering its last state, so I don't always tap the checkmark again for every review.