I have a fairly new site that has around 83 pages. A few days ago, Google indexed 50 of my new pages. Now most of these pages have been deindexed. It is normal for Google to randomly index and deindex new pages?
It's normal that Google indexes most of the new web pages on a website, then keeps in the index those with any inbound links or high internal linking.
This happens when your website is fairly new. Indexing will get normalized once your domain has aged and once you have many quality inbound links. Deindexed pages will get re-indexed. I am speaking from experience.