I am working on a wordpress v5.2.4 site that has Arabic language and words in URL which is causing an odd issue.

I create a category: خطوط إرشاد which is creating a slug url: www.mysite.com/خطوط-إرشاد

The encoded URL is

www.mysite.com/%d8%ae%d8%b7%d9%88%d8%b7-%d8%a5%d8%b1%d8%b4%d8%a7%d8%af/

Which loads fine but when I click refresh I get a 404 and the uRL becomes (in both Chrome and Firefox latest)

www.mysite.com/%D8%AE%D8%B7%D9%88%D8%B7-%D8%A5%D8%B1%D8%B4%D8%A7%D8%AF/

I dont know why the URL is changing to capital characters or why capital charater encoded URL wont work as my understanding is that encoded characters are the same in both lower and upper cases ie %D8 == %d8

Any help is appreciated.