DNSSEC is enabled as well which might cause issues if you’re lately changed something. Therefrom, it is the reason why it doesn’t work for newsletter sub-domain.
Nevertheless, regarding the above error once you’re on Cloudflare, may I ask what SSL option have you got selected under the SSL/TLS tab at Cloudflare dashboard for your domain ( Flexible, Full, Full Strict … )?
Before moving to Cloudflare, was your newsletter sub-domain working over HTTPS connection?
Nevertheless, usually steps for troubleshooting the SSL:
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 / Plesk panel / 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 set to Full (Strict).
THanks, My site doesn’t use Cloudflare anymore…The newsletter.buywiththrills link is going throughSender.net server. I found Cloudflare giving several issues on Wooxommerce, rending my site unusable,