The sitecheck scan results shows the harmful js script in your webiste. Mostly this script hides under theme header file (wp-content/themes/theme_name/header.php) and shows up in website source page. This type of js script hosts a malicious url which is blacklisted by Google. Right now we are not sure about the source for this type of malware injection. There may be other malicious script or file among your website files which is injecting this js script into the header files. You can use any rated security plugin like Wordfence to know more about malicious file. If it doesn't help then you may need to contact vendor who can manually check, remove malware and fix the site.
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