Hash4seo, Welcome to WebmasterWorld
...content of 20 to 30 words copied and search on google not showing domain.com and 20 to 30 words copied and searched it's displaying on SERPs.
Did you search these with or without quotes? I generally find that quoted
unique text strings are the best way to find whether something's in the index.
I've also found that long text string searches generally don't tell you anything if the text string is not in quotes. Without the quotes, particularly on a long string, there are generally too many other factors for Google to assign a meaningful ranking. No matter what Google's current algo, I've felt that context and inbound links have had a lot to do with how these text strings rank.
Also, when using quotes, choose your text string from the body of the page. The meta description element, eg, is not
used by Google for ranking, and I've seen people waste a huge amount of time and effort trying to find their pages by searching for a string taken from their description.
Additionally, so far primarily during the month of April 2019, Google has had some major indexing bugs, enough that I'm tending to lump all reports like yours together and simply say that things haven't been fixed yet, though there are recent signs that results are returning. See this thread, and read other threads it references.... April 2019 Google indexing & reporting bugs continue... It's not you! https://www.webmasterworld.com/google/4943488.htm
How have you been getting Google to see and index your pages? Are you using the submission tool in the GSC. If so, increasingly Google has been raising the bar, and I'm thinking that the submission tool has become less effective as a way to keep your pages in the searchable index. Inbound link quality, among other things, is having a lot more to do with it.