Why website included a sudden drop in recent days?
 

This is normal in a short time, the search engine included, the part of the information content is fixed in a library, after a period of precipitation, important or high-quality information will be removed. After a period of observation, if it continues to decline, or suddenly disappear. This is not normal, you should check in to check whether there are signs of cheating, or whether it is associated penalties, or human intervention.

It is very normal for a short span of time as important details and information are locked in the library. But if it is taking time it can be a penalty and then we have to look for the faults which can be punished by the SE.

Search engines are getting more stricter day by day.