Depopulate not working for populated docs inside array

[LiaanM]

Do you want to request a feature or report a bug?
Bug

What is the current behavior?
A schema containing an array of documents with a nested reference inside of the document in the array does not depopulate correctly.

If the current behavior is a bug, please provide the steps to reproduce.
The following is a test to reproduce the error. The band.members and band.lead is depopulated correctly, but the band.embeddedMembers are not.

it('depopulate all should depopulate nested array population', async function() {

     const Person = db.model('Person', {
          name: String
      });

      const Band = db.model('Band', {
          name: String,
          members: [{ type: Schema.Types.ObjectId, ref: 'Person' }],
          lead: { type: Schema.Types.ObjectId, ref: 'Person' },
          embeddedMembers: [{
              active: Boolean,
              member :{
                  type: Schema.Types.ObjectId, ref: 'Person'
              }
          }]
      });

      const people = [{ name: 'Axl Rose' }, { name: 'Slash' }];
      try {
          let docs = await Person.create(people);
          let band = {
              name: 'Guns N\' Roses',
              members: [docs[0]._id, docs[1]],
              lead: docs[0]._id,
              embeddedMembers: [{active:true,member:docs[0]._id},{active:false, member:docs[1]._id}]
          };
          band = await Band.create(band);
          await band.populate('members lead').populate('embeddedMembers.member').execPopulate();
          assert.ok(band.populated('members'));
          assert.ok(band.populated('lead'));
          assert.ok(band.populated('embeddedMembers.member'));
          assert.equal(band.members[0].name, 'Axl Rose');
          assert.equal(band.embeddedMembers[0].member.name, 'Axl Rose');
          band.depopulate();
          assert.ok(!band.populated('members'));
          assert.ok(!band.populated('lead'));
          assert.ok(!band.populated('embeddedMembers.member'));
          assert.ok(!band.embeddedMembers[0].member.name);
          return null
      } catch (err) {
          /* handle error */
          assert.ifError(err);
          return err;
      }
  });

What is the expected behavior?
The array with nested population should depopulate.
I suspect the $set is not taking into account the array indexes here :

mongoose/lib/document.js

Line 4206 in a803885

this.$set(key, populatedIds);

What are the versions of Node.js, Mongoose and MongoDB you are using? Note that "latest" is not a version.
Node.js -> v14.17.5
mongoose -> 5.13.8
MongoDB -> 5.0.2

[IslandRhythms]

The last console.log() returns false when it should return true

const mongoose = require('mongoose');
const {Schema} = mongoose;

const Person = mongoose.model('Person', {
    name: String
});

const Band = mongoose.model('Band', {
    name: String,
    members: [{ type: Schema.Types.ObjectId, ref: 'Person' }],
    lead: { type: Schema.Types.ObjectId, ref: 'Person' },
    embeddedMembers: [{
        active: Boolean,
        member :{
            type: Schema.Types.ObjectId, ref: 'Person'
        }
    }]
});

const people = [{ name: 'Axl Rose' }, { name: 'Slash' }];

async function test() {
    await mongoose.connect('mongodb://localhost:27017/test', {
        useNewUrlParser: true,
        useUnifiedTopology: true
      });
      await mongoose.connection.dropDatabase();

      
try {
    let docs = await Person.create(people);
    let band = {
        name: 'Guns N\' Roses',
        members: [docs[0]._id, docs[1]],
        lead: docs[0]._id,
        embeddedMembers: [{active:true,member:docs[0]._id},{active:false, member:docs[1]._id}]
    };
    band = await Band.create(band);
    await band.populate('members lead').populate('embeddedMembers.member').execPopulate();
    console.log(band.populated('members')); //true
    console.log(band.populated('lead')); // true
    console.log(band.populated('embeddedMembers.member')); // true
    console.log(band.members[0].name, 'Axl Rose'); // true
    console.log(band.embeddedMembers[0].member.name, 'Axl Rose'); // true
    band.depopulate();
    console.log(!band.populated('members')); // true
    console.log(!band.populated('lead')); // true
    console.log(!band.populated('embeddedMembers.member')); // true
    console.log(!band.embeddedMembers[0].member.name); // false
    return null
} catch (err) {
    /* handle error */
    console.log(err);
    return err;
}
}

test();