I tried using delay(50) on each API call, but I still get 429 Too Many Requests. Back-end is Laravel, what’s the best way to prevent this in Angular or should this be handled by back-end Laravel?

My code look like this

export class PdoProgramComponent implements OnInit {
  ngOnInit() {
    this.loadPdoPrograms();
  }
  // Load all PDO programs from DB
  loadPdoPrograms() {
    this.isLoading = true;
    this.pdoService.getAssigendPdos().pipe(
      take(1),
      map(res => this.sortPdosByName(res.results.pdos)),
      switchMap(pdos => this.validatePdoPrograms(pdos)),
      catchError(err => {
        this.showAlertSavingFailed();
        return of([]);
      })
    ).subscribe({
      next: (pdos: Pdo[]) => this.pdos = pdos,
      complete: () => this.isLoading = false
    });
  }
  validatePdoPrograms(pdos: Pdo[]): Observable<Pdo[]> {
    return from(pdos).pipe(
      concatMap(pdo => of(pdo).pipe(
        delay(50), // Delay each call by 50 milliseconds
        switchMap(() => this.pdoService.getSpecificPdoAdvocaiesPrograms(pdo.id).pipe(
          take(1),
          map(res => {
            const pdo_advocacies = res.results.pdo?.pdo_advocacies;
            pdo.editRequiredCount = 0;

            pdo_advocacies.forEach(advocacy => {
              if (advocacy.advocacy !== 'Unrestricted') {
                pdo.editRequiredCount += advocacy.pdo_programs.filter(
                  program => program.admin_advocacies.length === 0 ||
                    !program.admin_beneficiary_category ||
                    !program.program_category
                ).length;
              }
            });

            return pdo;
          })
        ))
      )),
      toArray()
    );
  }

}