What could be more irritating about the fact that you receive a rather threatening and suspicious message from Blogger stating that your legacy Blogger url can no longer automatically redirect to your new domain?
Going through checks and such to attempt to resolve the issue, you end up pretty much at a dead end. Until you realise that Cloudflare is messing up with Blogger's domain detection system.
But what about Cloudflare? Cloudflare proxies data over to your visitor, and does so indiscriminately, in such that Blogger's fraud domain/moved blog detection system cannot distinguish a difference between the Blogger page pointed by Cloudflare or an entirely different domain.
But fixing this issue, and hence removing Blogger's redirection notice: "This blog is not hosted by Blogger and has not been checked for spam, viruses and other forms of malware." is simple.
Step 1:
Manage your DNS for the domain in question from Cloudflare
Step 2:
Scroll down to the subdomain that contains the CNAME entry of your blogger page
Step 3:
Click on the cloud icon as shown on the above image, to disable the features of Cloudflare blocking Blogger from detecting your domain properly
Step 4:
Save the changes, by clicking on "I'm done entering my DNS records".
And that's it! In next to no-time, Blogger will acknowledge these changes and you'll be redirected automatically...