Edit Mode in sets cookie to en-us whereas site sets to en-gb

I am usig CMS 11 version. However, edit mode sets culture to en-us even when my site is in en-gb. So, when I open both in same browser, language gets set to en-us and en-gb for edit mode and site respectively. I found similar issue in the following post but there is no solutions.

https://world.episerver.com/forum/legacy-forums/Episerver-7-CMS/Thread-Container/2013/5/Edit-Mode-in-English-when-English-is-not-a-site-language/

I have webconfig setting as below.

<globalization culture="en-US" uiCulture="en" requestEncoding="utf-8" responseEncoding="utf-8" 
resourceProviderFactoryType="EPiServer.Framework.Localization.LocalizationServiceResourceProviderFactory, EPiServer.Framework.AspNet" />