I see the same error code, but in my own browser. So seeing how your domain is using Cloudflare, it means Cloudflare does not have an SSL certificate for your domain name to use on the frontend.
Cloudflare should do this automatically. Please make sure you have the “Universal SSL” option enabled in Cloudflare.
It’s also recommended to setup a certificate on your hosting account to secure the connection between Cloudflare and our servers. But that won’t fix the issue, this is a problem on the Cloudflare side.