function DeleteOne cannot directly delete rows in mongoDB

[fexli]

Describe the bug
using the following code (rows are created before delete function)

taskId := task.ID // typeof: *primitive.ObjectID ,sample: ObjectID("62c6ddc7fa2cd2b1c1642c2c"
mgm.Coll(&Task{}).DeleteOne(context.Background(), bson.M{"_id": taskId})

could delete the target row but leaves the data with field _id left

I check the database through mongodb tool and find that there are many documents with the same ID in the table

search script:

db.task.find({})
   .projection({_id:ObjectID("62c6ddc7fa2cd2b1c1642c2c")})
   .sort({_id:-1})
   .limit(50)

and the result like following ():

Key | Type | Value
(1) 62c6ddc7fa2cd2b1c1642c2c Document
{
    _id: ObjectID("62c6ddc7fa2cd2b1c1642c2c")
}

it can't delete the row completely, I'm not sure if this is caused by my operation or understanding mistake.

Expected behavior
Delete the whole document completely (not even _id field)

Screenshots

backup_db_search_imgur

Environment (please complete the following information):

• Windows 10 x64
• mongodb.net official database

[fexli]

use find and not to use projection, sorry for my misunderstanding.