If possible, put your site into "Maintenance Mode" via your hosting panel to prevent visitors from seeing the defacement or potentially interacting with malicious scripts.
Even though the site is hacked, take a manual backup of your current files and database. This ensures you don't lose any data during the cleanup process. Hacked By Mr.qlq Fix
Tools like Sucuri or Wordfence can block malicious traffic before it reaches your site. If possible, put your site into "Maintenance Mode"
Running an old version of WordPress, Joomla, or Drupal. Hacked By Mr.qlq Fix