Indeed jobs get indexed by Google faster than your career site pages and your SEO suffers. Unique jobs from your website become duplicate of Indeed content cached earlier. Which reduces the amount of relevant content cached, decreases your search engines positions and diminishes targeted job seeker traffic.
Aggregators are great to help your site get applications fast, but they will undermine your SEO and value of your site in the long run.
Traffic vs conversions
Review the number of visits from aggregator site. Check the bounce rate, time spent on site and actual applications you are getting.