Can't restore WordPress default Caterory Permalinks

I’ve been playing around with different permalink structures in WordPress, and eventually wanted to go back to the default permalink structure i.e. evreimir.com/wp/?p=post_id, for a number of reasons not important to mention in this question. The permalinks work fine for posts and pages. However when it comes to category permalinks, they appear as follows:

https://evreimir.com/wp/?category_name=%category_slug%

This results in a 404 error for categories that have none latin (russian) slugs, but works fine for categories with latin slugs such as

https://evreimir.com/wp/?category_name=america

In addition when trying to access a category through the default permalink structure:

https://evreimir.com/wp/?cat=1

it works fine which is strange

Looking at the .htaccess file this is what is in there:

# BEGIN WordPress

# END WordPress

Can someone please tell me how to restore the default permalinks for categories. Thanks in advance

P.S. The urls I gave are real and are of the site in question.