Some weird users in database

Might be this is due to the Spam. Diable use registration under the General -> Settings if you don’t need registration on the front-end or use the captcha or other spam protection plugins.

Regarding the backend -> Have you checked the wp_usermeta table if any role assigned to those users or not? Check user roles for those users.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)