Virus sweeper

Try a reboot.

If that fails, then try removing whatever Safari extensions are installed.

If that fails, remove any add-on anti-malware or anti-virus packages, any add-on cleaners or optimizers, and any add-on network-monitoring and firewall tools, each removed per the vendors' instructions, and then reboot.

Then if all of that fails, download and invoke and post the configuration report from EtreCheck here, opening a reply here and then using the (highlighted) button that looks like a printed page to get a text input box big enough to paste the entire configuration report here.

Quit Safari then while pressing and holding the shift key launch Safari. This will start Safari in a clean state.