I see an issue with the SSL first as far as getting the warning, then being redirected from www to non-www then to dan on which I see some iFrame? and SSL_ERROR_BAD_CERT_DOMAIN error.
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 … )?
Unfortunately, I have to say you’ve selected the wrong one. Flexible SSL is really not recommended to use as there could be multiple issues caused by using it as follows at the below article like Mixed Content or Redirect Loops, etc.:
You should fix the SSL first, therefore select the correct one → Full (Strict) SSL:
To answer your question, YES you can use Cloudflare if you have a Blogger site with a Custom Domain but NO you can’t if you are using a *.blogspot.com address. You go to their website (cloudflare.com) sign up for an account (I recommend the FREE plan), attach your domain to Cloudflare, change the Name Servers from your domain registrar to Cloudflare’s Name Servers (Cloudflare will provide this information) and voila you’re good to go.
Maybe the SSL certificate at your origin host/server expired?
Otherwise, your Blogger setup and using a free blogger in domain name might not be compatible?
You could determine this by:
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.
Only then should you un-pause Cloudflare and double-check your SSL/TLS setting to make sure it’s Full (Strict).
UPDATE:
Kindly, check the blogger settings, the other user seems to have it sorted out?