bug(Timepicker): valueChanges-event is called during initialization

[awallat]

Is this a regression?

• Yes, this behavior used to work in the previous version

The previous version in which this bug was not present was

No response

Description

When I register to the valueChanges of a form-group, then I get a valueChange during initialization, which is different from other components. I prepared a StackBlitz for this where I have datepicker and a timepicker. Only when the timepicker is present, the form emits a valueChanges-event.

Reproduction

StackBlitz link: https://stackblitz.com/edit/iar2r8q6?file=src%2Fexample%2Ftimepicker-overview-example.html,src%2Fexample%2Ftimepicker-overview-example.ts&startScript=start
Steps to reproduce:

1. Open the developer console and watch for the logs
2. In the beginning there is no component in the form.
3. After 500ms the datepicker is added and no valueChanges-event is emitted.
4. after another 500ms the timepicker is added, but here a valueChanges-event is emitted.

This behavior is not consistent in my opinion.

Expected Behavior

The timepicker should not send a valueChanges-event during initialization.

Actual Behavior

The timepicker sends a valueChanges-event during initialization.

Environment

• Angular: 21.0.0
• CDK/Material: 21.0.0
• Browser(s): Chrome
• Operating System (e.g. Windows, macOS, Ubuntu): macOS, Windows