What is X-Redirect-Agent header?

If your WordPress curl
[code:1:822a80cc7d]curl -v https://www.domain.com/page/[/code:1:822a80cc7d]

Results in this header
[code:1:822a80cc7d]X-Redirect-Agent: redirection[/code:1:822a80cc7d] then the plugin Redirection is active , check your redirects in WP-admin!