Thanks for the context.
I think the drop in DA and the increase in internal links are both things you should be paying attention to, for different reasons - they're almost certainly unrelated.
When you say "the most recent crawl by a Googlebot" - are you talking about server log data here? Or Moz sitecrawl? I should stress Moz is not Googlebot and could never emulate Googlebot behaviour - we are crawling URLs discovered by linking on your site, so naturally won't uncover a botched migration after the fact.
As for the incrase in internal links, I notice they're also marked as nofollow in many cases. Have a look at the "all crawled pages" list, and see if you can find anything that looks like a crawl trap. It looks very likely to me that your site is generating a large quantity of garbage URLs - perhaps through pagination, facets, or something like that. Looking in your own source code for "nofollow" might help you to narrow this down, as we can see over 120k of these internal links are nofollow.