Hey people.

I have a weird issue which I hope you could help me out.

So one of my pages is not showing for a specific key phrase, especially for UK users/IPs on google. It may not appear in SERP for a week but one day it appears and stays at the top, on 1st result for maybe 12 to 24 hours and huge amount of traffic flows into my website.

The website Core Web Vitals is perfect both for Mobile and Desktop.
The content including that specific page is super optimized and high quality to the bits, I used YOAST and Semrush and it has very high score.
The key phrase difficulty is very easy actually
The website has been online since 2016
I have another website, wrote an article for the same subject, used the same tactics and it was indexed after 6 hours on page 4 on SERP and now stabilized on page 2.

My question is, why does my URL disappears for a few days and then emerges for a few hours, at 1st line of SERP and then disappears.

All other pages are doing fine for other key words and phrases.

The funniest thing for me is that I have analyzed all my competitors:

-Their SEO score on the page for the key phrase is terrible.
-Their Core Web score is trash

And yet they have no issues and always stay there without vanishing.