formfields of FormGroup are not getting disabled if formGroup is disabled using expressions

[Sankey1506]

Description:
formfield inside the formGroup is not getting disabled. Fields has to be disabled explicitly using expression.
This seems to be working v5.

Minimal Reproduction:
https://stackblitz.com/edit/angular-gvuzak-thkuew

Other Details:
I have to disable formgroup and its containing fields using only expressions of formGroup.

[aitboudad]

disabled property is only taken when the fieldGroup has a key else it'll be ignored.