Unexpected Index deletion

mongoDB is deployed in clustered mode(replica set) as a statefulset in AWS EKS.
It’s been 2 years since the index is created. Now one of the index got deleted.
We didn’t perform deletion on index.
But we deleted few data from the collection. Can anyone explain how this index is got deleted ?

mongodb version 4.2.7

Hi @Sebin_Sebastian and welcome to the MongoDB community forum!!

MongoDB does not have an automatic mechanism to delete indexes, so it’s possible that the deletion of the index was due to user action or application code.

Could you help me with more details on what actions have been performed on the database or if you could see any weird behaviour or warning messages in the log files during the period when index was deleted.
The log would look something similar to below:

2023-03-28T13:04:36.524+0530 I COMMAND [conn7] CMD: dropIndexes test.sample: “name_1”