itestにリダイレクトされるのはこれのせい

https://kes.5ch.net/test/read.cgi/donguri/1718895589/312-

We are going to start using itest as the default browser for PC soon.

5ch is now penalized by search engines for having two versions of the same site.
We need to consolidate into one platform, and itest has more functionality than read.cgi.

It will default to itest, but there will be a button for those who want to use read.cgi.