What is it?
Temporary redirects (i.e., a 302, 303 and a 307 redirect) mean that a page has been temporarily moved to a new location. Search engines will continue to index the redirected page, and no link juice or traffic is passed to the new page, which is why temporary redirects can damage your search rankings if used by mistake.
How to fix it
Review all pages to make sure the use of 302, 303 and 307 redirects is justified. If so, don't forget to remove them when they are no longer needed. However, if you permanently move any page, replace a 302/303/307 redirect with a 301 one.