May I ask have you tried using a different Web browser, or Incognito mode (Private window)? Does the same error appear over again?
I was presented with error SSL_ERROR_BAD_CERT_DOMAIN while visiting your Website.
Kindly, make sure you have got a valid SSL certificate covering your domain name installed at your origin host/server:
Use the “Pause Cloudflare on Site” option from the Overview tab for your domain at dash.cloudflare.com .
The link is in the lower right corner of that page.
Give it five minutes to take effect, then make sure site is working as expected with HTTPS without any error
Check with your hosting provider / cPanel AutoSSL / Let’s Encrypt / ACME / Certbot and manually click to renew it
Only then, when your website responds over HTTPS, you should un-pause Cloudflare and double-check your SSL/TLS setting to make sure it’s Full (Strict).