If your WordPress suddenly give redirection URL that you don't know and you believe did not set anything, then it is mostly your WordPress got compromised. Here are list of steps you should taken :
Set to Maintenance
First action to do is set your WordPress into Maintenance mode. You can install a plugin called "maintenance" and then set to active. You can also put some words into it. This time when visitor visits your website, it will have a maintenance notification.
Backup All Files and Databases
Next is make sure you do backup all files and databases from your WordPress. Make sure you download all the files to your local laptop or computer.
Remember Site Settings
It is very important to remember all the site settings whether it was plugins settings, or themes settings. Make sure you remember or do a screenshot to make it happen. Either smtp settings, theme settings, plugin settings, etc.
Last Working Website
Remember when is the last time your website working? This is very important as you can request a restore to us. However please take a note that a restore request may overwrite everything and fully rolled back to requested date settings.
Self Recovery
Yes, you should able to self recovery your WordPress website and it is doable. After you set to maintenance, full backup website, remember site settings, all you need to do is reinstall. First, reinstall WordPress core. Second, reinstall all the plugins. Third, reinstall the theme WordPress. So we need to make sure everything is reinstalled. You also need re-adjust the site settings.
After everything is reinstalled, make sure to deactive maintenance plugin. And try again to access your WordPress website, see if there is any redirection.