I had the same problem after changing the URL of a page. I found that issue occurred due to a plugin “Yoast SEO”. That plugin keeps old URLs and new URLs.If a page redirects unexpectedly or causes a redirect loop only when your plugin is active, this means a redirect has been added to your plugin. To solve this go to the redirects section under SEO plugin and delete the relevant redirect record.
For more details, you can refer here.
https://kb.yoast.com/kb/page-redirects-unexpectedly/