I honestly don’t know why I cannot access, but since even using a bypass proxy returns the same error, the issue does not seem to be on our end unfortunately.
Okay, let’s try different settings then. Instead of using the settings shortcode, please try this variation:
1. Turn off the search bar to only show the settings here: https://i.imgur.com/I5Aa74A.png
2. Then instead of the custom text widget, please try the regular search widget: https://i.imgur.com/MuOIOv3.png
That should basically yield the same result when using the settings shortcode.