I wanted to post an update in case anybody is in a similar situation.
After 2 appeals and almost 48 hours of downtime our suspension was finally lifted. In my last appeal, I wrote a list of all possible explanations/notes/comments I could think of that are at least somewhat related to the vague reasons provided in the original suspension notice.
Something in that list must have been it, because the suspension was eventually lifted. The worst part? I still don't know what was the specific grounds for the suspension in the first place and what we can do to make sure this doesn't happen again in the future.
Nobody on phone, chat or email support was able to provide me any clear answers. I can't even message the team that lifted the suspension after the fact.
All in all, a terrible customer experience on our end, especially for an application of our magnitude...