The pages on the front-end (ie viewing published pages) seem to not be affected, it’s when adding menu items and clicking save menu I’m redirected. Also when trying to navigate to my Theme Customiser (I’m using DIVI theme for reference). I can access Theme Builder, Role Editor, Theme Options, and many other pages without issue, but cannot access Theme Customiser.
My first guess is that this could be an issue with website URL settings. Perhaps you are looking at the www subdomain but the URLs of your website are without www? Or the other way around? The different domains could result in cookie related restrictions too.
Maybe check your browser’s Network tab in the Developer Tools? That shows you which URLs and domain names are being requested? This should show you which URLs you’re sent to while being redirected to the Google cookie page.