bug(chips): input rendering its placeholder when disabled

[jhthompson]

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

19

Description

When there is an <input> in a disabled <mat-chip-grid>, the input's placeholder still renders. This is confusing, because the placeholder is often a value like "Enter new ...", which implies the control is enabled.

The behavior of rendering the placeholder in a non-focused mat-chip-grid also seems not well defined, as there have been other issues complaining about both behaviors:

• docs-bug(MatChips): Input placeholder is not showing if not focused #26883
• Chip input in form field doesn't show placeholder #16380

Example

Comparing the v19 chips examples to the v20 chips examples:

	v19	v20
Enabled
Disabled

Reproduction

Steps to reproduce:

1. Visit v19 chips docs: https://v19.material.angular.dev/components/chips/overview
2. Disable the form control in "Chips with form control" example
3. Notice the placeholder does not render
4. Visit v20 chips docs: https://v20.material.angular.dev/components/chips/examples
5. Disable the form control in "Chips with form control" example
6. Notice the placeholder does render

Expected Behavior

The <input> placeholder should not render when disabled.

Actual Behavior

The <input> placeholder renders when disabled.

Environment

• Angular: 20.3.9
• CDK/Material: 20.2.9
• Browser(s): Chrome
• Operating System (e.g. Windows, macOS, Ubuntu): Windows