load checkbox check in reactive form

I have this checkbox that I load from a list with ngfor. In the function to load the checkbox is found in the ngOnInit()

<form [formGroup]="updateUserFormEducation" (ngSubmit)="updateInfoEducation(updateUserFormEducation.value)"
            class="needs-validation" novalidate>

     <div class="bg-white p-3 rounded border-opacity-25" formGroupName="levels">
        <div class="form-check" *ngFor="let level of list_levels; let i = index">
            <input class="form-check-input" type="checkbox" [formControlName]="i" [value]="i"
            (click)="loadCourses($event)">
            <label class="form-check-label" [for]="level.id">
                 {{ level.name }}
            </label>
        </div>
    </div>

</form>

component.ts

updateUserFormEducation = new FormGroup({
    id: new FormControl(),
    level: new FormControl(),
    course: new FormControl(),
    subject: new FormControl(),
})


this.updateUserFormEducation = this.formBuilder.group({
     levels: this.formBuilder.group({}),
})

checkboxLevel() {
    this.list_levels = []
    this.levelService.getLevel().subscribe((levels: any) => {
        levels.map((level: Level) => {
            if (level.condition_level === 1) {
                this.list_levels.push({
                    id: level.id,
                    name: level.name
                })
            }
        })
    })
}

ngOnInit

the row.id is the id of the user.
getUserSubjectLevel returns what the user selected, then I compare the list that is loaded with that of the function

const levels = <FormGroup>this.updateUserFormEducation.get('levels');

this.userSubjectService.getUserSubjectLevel(row.id).subscribe((user_subjects_levels: any) => {
     user_subjects_levels.map((user_subject_level: any) => {
           this.list_levels.map((list_level: any, index: any) => {
               if (list_level.id === user_subject_level.level) {
                     levels.addControl(index, new FormControl(true));
               }else{
                     levels.addControl(index, new FormControl(false));
               }
           })
      })
 })

it throws me an error

but when doing it manually, it works. that’s an example

this.updateUserFormEducation = this.formBuilder.group({
     levels: this.formBuilder.group({
          0 : new FormControl(true),
          1 : new FormControl(false),
          2 : new FormControl(true),
     }),
})

so I don’t know what could be the error, if you can help me thanks