TypeError: Cannot read properties of null (reading '$implicit') with async pipe

Question

I'm trying to find out what is the reason of issue:

It raises for this part of code:

<div ngbAccordion #accordion="ngbAccordion" >
    <div ngbAccordionItem="first">
      <span class="body-medium-text-l" ngbAccordionHeader>
        <button ngbAccordionButton class="body-medium-text-m">{{ 'hub_repairs_open_requests' | translate }}</button>
      </span>
      <div ngbAccordionCollapse>
        <div ngbAccordionBody>
          <ng-container *ngFor="let return of dataService.returns | async"> <<== here
            <app-repair-row [return ]="return "></app-repair-row>
          </ng-container>
        </div>
      </div>
    </div>
  </div>

My investigation yielded no conclusions.