Waiting a month for editor to relay reviewer’s (second) response?

I have submitted my first 1st author paper in Nature Coms (via my supervisor) in my PhD. We got back some reviewer’s comments, then it was re-submitted.

Within a week of resubmission receipt, my supervisor said the reviewer’s response has been confirmed to be with the editor. It’s now been a month since then and we haven’t heard anything else.

I am wondering what might be going on. My supervisor was initially optimistic that it only took a week for the reviewers to respond, but he is also confused by the editor taking so long to inform us.