Reactive form async validation fires on change when updateOn: 'submit'

🐞 bug report

Affected Package

The issue is caused by package @angular/forms@9.1.5

Is this a regression?

Don't know

Description

Async validation for FormGroup fires on every input change event when updateOn: 'submit' is set.

🔬 Minimal Reproduction

Grab the example form validation from docs (https://angular.io/guide/form-validation) and change Reactive form declaration like this

this.heroForm = new FormGroup({
  'name': new FormControl(this.hero.name, {
    validators: [Validators.required, Validators.minLength(4), forbiddenNameValidator(/bob/i)],
    updateOn: 'change'
  }),
  'alterEgo': new FormControl(this.hero.alterEgo, {
    validators: [Validators.required],
    updateOn: 'change'
  }),
  'power': new FormControl(this.hero.power, {
    validators: [Validators.required],
    updateOn: 'change'
  })
}, {
  validators: identityRevealedValidator,
  asyncValidators:  [this.alterEgoValidator.validate.bind(this.alterEgoValidator)],
  updateOn: 'submit'
});

🌍 Your Environment

Angular Version:

Angular CLI: 9.1.4
Node: 12.13.0
OS: win32 x64

Angular: 9.1.5
... animations, common, compiler, compiler-cli, core, forms
... platform-browser, platform-browser-dynamic, router, upgrade
Ivy Workspace: Yes

Package                           Version
-----------------------------------------------------------
@angular-devkit/architect         0.901.4
@angular-devkit/build-angular     0.901.4
@angular-devkit/build-optimizer   0.901.4
@angular-devkit/build-webpack     0.901.4
@angular-devkit/core              9.1.4
@angular-devkit/schematics        9.1.4
@angular/cli                      9.1.4
@ngtools/webpack                  9.1.4
@schematics/angular               9.1.4
@schematics/update                0.901.4
rxjs                              6.5.5
typescript                        3.8.3
webpack                           4.42.0

Anything else relevant?

[cosminv6u]

If you remove updateOn: 'change' from all controls the async validator (actually all validators) will be called at submit only. But I guess that’s not the point, we should be able to mix and match them with different configurations.

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