@krishnaverma it's a bug.
https://www.seroundtable.com/google-search-bug-one-result-33780.html
But even it is a bug, SEO is dying. People who disagree are either link sellers or haven't been actively keeping track of the SEO game and just being in denial. I've been in this SEO game for years and I've met many other webmasters whom are into the SEO game for nearly a decade and we all agreed on the same thing.
Whether is it how Google obliterate whitehat sites in the recent core update, or throttling traffic. Google have been going to great extremes to reduce organic traffic.
Even if it is not algorithm updates, they are actively changing the search results layout to be very distracting to users. Just search for anything and you will see a big shopping ad panel at the top, followed by 4 paid listings, then sometimes "People Also Ask" or Youtube panel, only then they start showing sites ranking organically. This will reduce your CTRs tremendously. As I've always said, if you all don't believe me, just log on to your Google Search Console and see your performance analytics - you will notice the "impressions" and "clicks" are getting wider and wider apart,
especially after the May core update when they introduced that shopping ads panel.
So even if you do ultimate SEO like building quality links, put up quality content, and so on... The ROI isn't as profitable as in the past anymore.
I highly advise any of you to start finding alternatives or a backup plan.