This is a known Google soft penalty in order to contain spam contents and domains, but unfortunately, this thing penalized a lot of good, clean, and legit blogs, and when you caught this penalty, in 99% cases, you will never recovered.
It will only shows 1,2,3,4,5,6,7,8,9,11, or simialr numbers when you site:yourdomain on Google.
I found this thing around 2019, and it still exists till today.
A way to identify this: first post more than 20-30 articles on your blog, and if after several months, it still shows only several pages when you site: your domain, then it mostly caught this thing.
It will only shows 1,2,3,4,5,6,7,8,9,11, or simialr numbers when you site:yourdomain on Google.
I found this thing around 2019, and it still exists till today.
A way to identify this: first post more than 20-30 articles on your blog, and if after several months, it still shows only several pages when you site: your domain, then it mostly caught this thing.
More info: https://www.blackhatworld.com/seo/anyone-site-only-4-results...