Uploading speed is getting slow continiously in firebase angular

Think you found a bug?
=======================
Hi Team,
We have made web application where we are uploading multiple images in batches using angular and firebase. but, when we start to upload image more than 5000 -6000.intially uploading speed is good till approx 1000, after that uploading speed is going decrease continiously.it is so frustrating for us. Please help on that.it is very critical for us
I am adding reference code which we are using.
CODE:--
const path = `users/${this.user.uid}/${this.projectName}/${this.file.name}`;
// const path = `${this.projectName}/${this.file.name}`; // path to upload demoproject
this.fileName = this.file.name;
// Reference to storage bucket
const ref = this.storage.ref(path);

// the main task
const current = new Date();


const timestamp =performance.now();
// console.log("start Time"+ timestamp)
let endstamp;
// var counts=0;
this.startUpload
this.task = ref.put(this.file, {
customMetadata: { projectName: this.projectName, contentType: 'image/jpeg' }
});

this.task.catch((err: any) => {
console.warn('upload error==>', err.code);
this.uiService.showSnackbar(`${err.code}: error occurred`, null, 3000);
this.uploadFailed = true;
});

let flag = false;
this.snapshot = this.task.snapshotChanges().pipe(
finalize(async () => {
this.downloadURL = await ref.getDownloadURL().toPromise();......................
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### Version info

**Angular:**--Angular CLI: 9.1.13

**Firebase:**:11.2.0

**AngularFire:**:5.4.2
Node: 16.15.1
OS: win32 x64

### How to reproduce these conditions

**Failing test unit, Stackblitz demonstrating the problem**

### Expected behavior

Uploading speed for all image should be same irrespective of internet speed.

### Actual behavior

when you upload multiple image in batches more than 5000 images. then initially uploading speed is same but when upload start from more than 1000..then uploading speed is going decrease continiously.

Start with the provided Angular upload code and the Angular 9.1.13, Firebase 11.2.0, and AngularFire 5.4.2 version details. Reproduce uploads in batches exceeding 5,000 images, compare throughput before and after roughly 1,000 uploads, and identify whether the reported continuous slowdown is reproducible.

Written by the indexing model from the issue text.