Google assigns every site a specific "Crawl Budget"—the number of pages it is willing to crawl on your site per day. If your server is serving up FU-10 responses, two things happen:

Go to Google Search Console > Indexing > Pages. Look for the category or "Not found (404)" or "Crawled - currently not indexed." Sort by the reason. If you see a pattern of URLs that look valid but are being excluded, you have an FU-10 anomaly.