After you update the Conversion Kit, guest account features such as sign-in modals and wishlist sync prompts may appear on your site, even though you never turned them on.
Why this happens. This is a known behavior introduced in Conversion Kit version 1.38.0. When a site upgrades from an older version, a settings migration can automatically enable guest account features, even on sites that never had them turned on.
What you can do. If these features appear unexpectedly after an update, contact support. Support can disable them for your site to restore your previous behavior.