Hey Christopher, Dave from the Help Team here.
It looks like we crawled less pages than from the previous week which could correlate with a change in issues.
Basically, the crawler finds pages by crawling all of the links on the homepage/front page and then crawling all of the pages those links took it to, and so forth, until all of the pages we can find under that directory are crawled. So, as long as we can find a link to a page, we crawl every available page within the scope of the Campaign.
If your number of pages crawled has dropped since your last crawl then my first thought would be that the links to those pages, or the pages themselves, may have been removed from the site.
If this is not the case, then there may be a new error that’s blocking us from reaching certain portions of the site. For example, if we find a new 404 error, the page may have previously been linking to the pages that are missing from your most recent crawl, so we can no longer access the links to those pages. This Crawl Errors guide (https://moz.com/help/guides/moz-pro-overview/site-crawl/fixing-issues) is the best place to start to understand and resolve crawl errors.
If you’re still stuck, or have any other questions, please do let me know!