I hope this not only happening in my blogs,  my Blogger RSS feed sitemap Drops from 500 post to 151 posts. now I have 500 Index posts while submitted posts drops to 15,  both my blogs are running on blogger platform .

If you look at below picture I have 2,398 indexed posts but from the 25 November suddenly drops submitted post to 1,805. How the will affect my site health will I also lose my index pages. I am worried now. Will dis affect SEO of my Site