Compound index is not being used for aggregation match clause

Working with Data
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2

You have equality match on the field index but you do not have any compound index that has that field as a prefix.

See Performance Best Practices: Indexing | MongoDB Blog and pay attention to the ESR rule.

could be written as

"index" : "5ecec41e1c3b9000e12c1225"

can be simplified to

{
  "auction.date": {
                "$lte": "2022-01-26T23:59:59.999Z" ,
                "$gte": "2021-11-26T00:00:00.000Z"
              }
},

and when these simplifications are done you can forgot the explicit $and and write the whole thing as:

{
  $match :
  {
    "index" : "5ecec41e1c3b9000e12c1225" ,
    "auction.date" :
    {
      "$lte" : "2022-01-26T23:59:59.999Z" ,
      "$gte": "2021-11-26T00:00:00.000Z"
    } ,
    "is50PercentageOffAverage" :
    {
      "$exists" : false
    }
  }
}

Finally, if is50PercentageOffAverage:{$exists:false} is part of you main use-cases you might consider Partial Indexes.

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