Crawlers act on codes, not on what the page says. A "page not found" message returned with a 200 is a soft 404: the engine keeps the URL, indexes an error message and wastes fetches on it. Conversely, a genuine 410 tells the engine the resource is deliberately gone and is processed faster than a 404.
Repeated 5xx responses are the most damaging of all, because they signal an unreliable host: crawl rate drops, and recovery lags well behind the fix. If a load test or a bot wave is causing them, that is an infrastructure problem with a direct SEO cost, not a separate concern for another team.