Forwarding subdirectory under a main site to a subdomain

I have a main site that is deployed on Netlify eg :

And I have a subdirectory under this main site called blog eg :

As per the below community post, I have created another Netlify site [sleepy-roentgen-3eb28f]
eg : with redirect rule in the site’s Ntelify.toml

And I followed the below too

But when I browse the URL on the browser for the blog content, I see the URL change from to instead of there being no change.

Hey @indcoder,
Is the expected result that* would redirect behind the scenes to*?

If that’s the case, could you please post the netlify.toml of your site? Thank you!