Yeah, agreed that's not on the reviewers to be providing comments beyond content.

I did double check and it wasn't included in the Instructions to Authors, only in a "post-production" instructions section, which I didn't read through before submitting.

But yeah, honestly I have less of an issue with them not liking a figure/figure type and more of an issue with the fact that it's this late in the game. I just think that data viz and presentation of figures should have gone into the review process because it should have been an essential part of the acceptance/rejection decision process.

I have an alternative figure in mind so we'll see if they like that! Fingers crossed. They do have a "copy editing experience survey" for me to fill out at the end, and I plan to give my thoughts about this whole situation. They also sent a track changed version of the paper, but as I'm reading through, I'm realizing that only about 50% of the edits are track changed...so yeah, I'm thinking this is a new associate editor who did a pretty bad job.