You have configured Ghost with the bare domain, so using www won’t work. You need to decide whether you want to use non-www or www, and then setup Google and Ghost correctly.
Google robot testing tool default redirects to my other website, and I have tried to check the blog through this. So I used this tool to check my robots.txt.
There is no error showing my robots.txt file.
I have cleared the cache from Cloudflare and re-submit it didn’t work.
Google robot testing tool default redirects to my other website
This will be the problem you need to solve. Google can’t see the website you’re trying to index. Using a different tool isn’t going to help fix Google.