Can you imagine the idolatrous shrines that would have been erected on such a spot if it were known where she was buried? Nobody knows when she died or where she was buried. Clearly, the scriptures did not think such information was of the least importance.
Here is a link to information you might find useful:
Mary the Mother of Jesus: https://www.thisisyourbible.com/library/show/1035
I hope you have found this helpful.