The crawlers get stuck in a loop requesting the dataset listing page with every. single. combination. of. facets. At essentially as fast as it can be pumped out or blocked.
Had one bot super interested in a single organization to the tune of 1000 r/min for 24+ hours. Realistic rotating user agents, realistic sec-* headers, no ip address seen more than a couple times in 10 minutes. The only commonality was the route.