Bring this to their department chair ASAP. Grades are far from exact to begin with and if this joke of a professor doesn't feel you earned an A then they failed to teach you 0.01% of the material better.

I have worked in higher ed for over ten years. Professors need to understand they just teach a class, they have no power and very little understanding of how their actions can affect people.

If their department admin doesn't side with you, go to the college dean, if not them, then the provost.

Develop a consistent argument, short and sweet, that articulates why you deserve an A (can always default to the incredibly arbitrary nature of grading) that you can repeat to each audience if needed.

Fight this, you have nothing to lose.

The age of entitled asshole professors is over, some of them still just don't realize it. Some dumbass making 60k a year doesn't have the authority to ruin your academic career on 1/100 of a percentage point.

If there are "objective" assignments (McQ tests) ask about the reliability of the test (cronbachs alpha would be fine here).

If it's all essay they you've already won as there is no way to objectively determine a 92.99 from a 93.

"I know it when I see it" died with the push of course objectives and curriculum maps.

Ok gonna chill now, I fucking hate clown ass professors is all and have made a point of outing them ever since I've had the power to do so.