[Input Group] Valid state shown for a field with no rules after switching `[formField]`

[viktorkombov]

Description

With Signal Forms, after [formField] is switched from a field that was invalid to a field with no rules, igxInput shows the VALID success state. The input remembers that the previous field had rules. Found in #17556, which adds the Signal Forms support.

Framework

Angular

Angular Version

22.1.x

Ignite UI for Angular Version

22.2.x (PR #17556)

Component / Area

Input Group

Browser

Chrome

Operating System

Windows

Command Not Working

No response

Steps to Reproduce

1. Check out branch rkaraivanov/fix-17556.
2. Add the following to a dev sample:

public plain = signal(false);
public model = signal({ validated: '', plain: 'anything' });
public userForm = form(this.model, p => {
    validate(p.validated, ({ value }) => value().length >= 3 ? undefined : { kind: 'short' });
});

<igx-input-group>
    <input igxInput [formField]="plain() ? userForm.plain : userForm.validated" />
</igx-input-group>

3. Run the sample. The input is bound to validated, which starts invalid.
4. Set plain to true, so the input is bound to plain, which has no rules.
5. Focus the input and mark userForm.plain as touched.

Actual Result

The input is in the VALID state.

Expected Result

The input is in the INITIAL state, the same as when it is bound to plain from the start.

Reproduction URL

#17556

Attachments

No response