Choose how much access the extension has.
Extensions may access the content of the webpages you visit. Check which extensions you have installed and make sure you’re familiar with what they do. See Change Extensions preferences in Safari.
Installing or uninstalling extensions, and turning them on or off, may take effect immediately or after you go to a new webpage or refresh the current page.
Important: The first time you open Safari, you get warnings about extensions that slow down browsing or are no longer supported:
Extensions that slow down browsing: The extensions will be turned off. You can turn on the extensions in Safari preferences.
Developer-signed .safariextz-style (legacy) extensions: The extensions won’t load and no longer appear in Safari preferences. You can’t turn them on.