I just took a look at the homepage of your site using my development tools and I think the JSON error you are asking about might be related to some updates you need to run. If you are running the latest version of WordPress (which is 5.6), as well as the latest version of your theme and all your plugins and still experiencing the issue then the problem might be the version of JQuery that your theme or one of your plugins is calling. I’d suggest installing Enable JQuery Migrate Helper https://wordpress.org/plugins/enable-jquery-migrate-helper/ or a similar plugin to see if that solves the problem.
Another thing, check that you have not turned on the “Disallow Search Engines from indexing this site” option at the bottom of the Settings → Reading page.
Hope one of these fixes helps you solve the issue.