unfortunately, mainly our blog and a couple of landing pages are not getting indexed by Google for a couple of months.
When we view the coverage report in Google Search Console we can find the pages under Coverage -> Discovered - currently not indexed.
We run the website under 2 languages (EN & German) and mostly german blog articles are affected. If we press the request indexing in Google Search Console
"Testing if live URL can be indexed" is loading...
until the error message 5XX Server Error appears which is then rejecting our indexing request.
Sometimes the index request goes through, but checking a couple of days later the page stays still unindexed. https://flair.hr/en/blog
I've had the same issue with one of my projects. For me, it seemed like a problem with the crawler, because my content was unique, high quality, and had no crawl errors. I tried requesting indexing repeatedly for a few weeks, and nothing happened. Finally, I made sure the page was well-linked within my website, and requested indexing of all of the linked pages, and that worked. I'm not sure if your problem is the same, but you could give it a try.
I know how to use Search Console but the I need your help to add Google Search Console code to the website. I don't where to add this code on the website.
I think this tool works by registering the site on Google's dev Search Console dashboard, I'm not sure what pieces you need to change in the code. Since this tool isn't directly to Prismic we don't have a guide to teach how to use it. That's why I highly recommend referring to Googles docs directly.