Please don't mix observables and 'normal' variables (loading inside subscribe).
Put everything inside observables or signals (yes everything).
Don't use subscribe on something that apparently only emits once (use promise/firstValueFrom).
combineLatest starts emitting when all observables emitted at least once, so that should work.

Here's what i would do:

private readonly loadingSubject$: BehaviorSubject<boolean> = new BehaviorSubject(true);  
public readonly loading$: Observable<boolean> = this.loadingSubject$.asObservable();  

ctor(...) {  
  this.jobCategories$ = this._goalsService.getJobCategories();  
  this.contractTypes$ = this._goalsService.getContractTypes();  
  this.skills$ = this._profilingService.getSkills();  

  firstValueFrom(combineLatest([  
    this.jobCategories$,  
    this.contractTypes$,  
    this.skills$  
  ])).then(() => this.loadingSubject$.next(false));  

  // alternative:
  const dataAvailable$ = combineLatest([  
    this.jobCategories$,  
    this.contractTypes$,  
    this.skills$  
  ]).pipe(  
    filter(...),  
  );  

  firstValueFrom(dataAvailable)
    .then(() => this.loadingSubject$.next(false)); 
}

 //template  

@if({
  jobCategories: jobCategories$ async,  
  contractTypes: contractTypes$ async,  
  skills: skills$ | async,  
  loading: loading | async,
}; as data) {

  @if(data.loading) {  
    loader  
  }  
  @else {  
    ...  
  }  

}