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.
Maybe someone had the same problem before.