I googled for a long time and tried to find something at https://www.sitemaps.org/protocol.html#index about gzip compression for sitemap INDEX files, but I couldn't find anything.
I have a very large dynamic site that is a directory of companies. I have 500+ sitemaps with 40,000 links each. All of these files are compressed with gzip and have the extension .xml.gz. A sitemap index file was created for these files, which I also decided to compress using gzip. Accordingly, its extension is also .xml.gz.
Now I am trying to index my site in the google search console. I add the sitemap index file to the sitemaps file section. The file is added, it is recognized as a sitemap index file, the status is Successful, but as a result, only 16 links from one sitemap0.xml.gz file were processed. At first I thought it was a temporary problem and they will be handled a little later. But I added this file back in April and I still have only 1 file out of 500+ processed and only 16 links from it.
At the same time, the console writes that it processed 400,000 links, and another 10 million links were found, but will not be indexed (without specifying any reasons, which I also do not understand).
So, looking for a bug, I want to ask if the sitemap index file can be gzipped or should it be left in its original xml form?
If possible, can someone tell me what to do? Just wait? I just haven't seen any changes in the console since April...
I honestly don't understand what the problem might be. Why were my 10 million links found but not indexed?