Is it normal if some pages of the site drop out of the search?

Question

Search engines

Hello connoisseurs.
There is a commercial site for the service sector.
There are more than 400 pages. New ones are being written all the time. Separation by metro and Moscow region.
Sometimes sites fly out in batches of 4-5 pieces from the search in the Yandex webmaster. These are actually not the most used pages. Should I be worried and run these pages for indexing again? Thank you for your attention to my question.

Answer 1

Look for the reason (spam, little information, duplicates, etc.).

Answer 2

Is it normal if some pages of the site drop out of the search?

It depends on what is considered "normal".
See the status in the "Yandex Webmaster - Indexing - Pages in search - Recent changes - Status and URL" dashboard. See screenshot.
You are interested in all the statuses in the "Deleted" column. Click on each one and see under what statuses the URLs drop out of the search results. Depending on the status, draw conclusions and take action.