Why has Safari suddenly begun to continuously refresh?

Are you running any anti - virus programs? Using a VPN?

Try setting up another admin user account in System Preferences/Users & Groups to see if the same problem continues. Please post back on whether or not this worked. Also try the Safe Mode. Please post back on whether or not this worked.

Isolating an issue by using another user account    

Safe Mode - About.       

If it works in the Safe Mode, try running this program when booted normally and then copy and paste the output in a reply. The program was created by Etresoft, a frequent contributor.  Please use copy and paste as screen shots can be hard to read. Click “Share Report” button in the toolbar, select “Copy to Clipboard” and then paste into a reply. This will show what is running on your computer. No personal information is shown. If the log won’t post, try posting it in Pastebin and provide a link in a reply. After pasting the report in a PasteBin page, go to the top of the page, and copy the address in the URL bar. Paste that in a new reply.        Pastebin.    

Etrecheck – System Information.      

Web site version if required.  https://etrecheck.com

Try clearing the cache and cookies.

Safari/Preferences/Advanced - enable the Develop menu, then go there and Empty Caches. Quit/reopen Safari and test. Then try Safari/History/Show History and delete all history items.  Quit/reopen Safari and test. You can also try try Safari/Clear History…. The down side is it clears all cookies. Doing this may cause some sites to no longer recognize your computer as one that has visited the web site.

Depending on the website that you are viewing, it may be signaling Safari to refresh its content. This is not as prevalent as it once was, but remains a possibility. If it is happening too often, then it may be a problem on the site, or a site you may wish to avoid in the future.

If you clear browser cache while still on a website, its cookie will be removed and immediately recreated. If you launch Safari while holding the shift-key, no site will load and clearing the browser cache will remove all cookies without any resetting themselves until you revisit that site again.

If the classic Facebook style continues to suppress frequent browser refreshes, then that may be the answer.