Shows the lightning-input-field not working after user input. (1): Click the button and see the lightning-input-field get updated. (2) Manually type something into the lightning-input-field and see it change. (3) Go back and click the button and see the update no longer work.

inputFieldIssue.html

<template>
    <lightning-record-edit-form
        object-api-name="Account">
    
            <lightning-input-field 
                field-name="Name" value={name}></lightning-input-field>
            
    </lightning-record-edit-form>

    <lightning-button label="Click to change name" variant="brand" onclick={handleClick}></lightning-button>
</template>

inputFieldIssue.js

import { LightningElement, track } from 'lwc';

export default class Example extends LightningElement {
    @track name = 'a';

    handleClick() {
        this.name = this.name + 'a';
    }
}

This is working as designed. From the lightning-input-field documentation:

If a user enters anything in an input field, you can no longer programmatically set the value of the field. The assumption is that there are unsaved changes that should not be overwritten. If you want to be able to overwrite user changes, you can use lightning-input instead.

Why wouldn't it also be assumed that user input collected from a lightning-input are unsaved changes that should not be overwritten? Seems totally arbitrary and a pain that we've lost the metadata-aware lightning-input-field.