Strange opencart redirect?

Question

opencart

there is a 301 redirect to the product, while it apparently redirects to itself. url does not change, but if you look at the network tab in the console, then the status is 301 and half of the sites checking the redirect say that it exists and half that it does not. There are no redirects in .htaccess. Of the seo plugins, there are FilterVier_SEO_v.2.3.47 and Seo Tags Generator, but I did not find any redirects there.
Where can I find this redirect?