G Deindexing Pages

G has recently been deindexing my sites, and I’m not sure what to make of it.

The content on the sites are very similar to other sites, but that has not affecting them before. An example is BB site advertising a Samsung tv. Of course the content would be the same on various sites. So I’m not sure I believe that’s the issue.

Do you think G would rather an exact copy of content, or similar (making some tweaks) to other content?

The sites haven’t been flagged, there’s no penalties, no spammy backlinks, or black hat methods. All very clean, good code, tags, markups, rich snippets, etc.

Did you check the new version of Google Search Console? It says which pages are not indexed and why. I noticed a few errors there and fixed recently.

I did. But I didn’t see where it showed the pages that were removed.

Also the site still ranks for a lot of the pages, but a bulk of them don’t show in the search results.

In the new panel, there's something called Index Coverage. When you open that report, it shows which pages are valid and which are excluded. For the excluded ones, it also gives a reason about why it is excluded from index.

Ah. I see that. But it doesn’t show the urls that were deindexed. It shows a number and says excluded.
But why? It doesn’t say.

When you click on excluded, a list shows up with reasons in the list below. All those errors are clickable and shows which url is excluded, so you can go into more detail in them. If that's a problem related to your site, you can figure it out from there.