Describe when to use repeat() more clearly

Description

if click 1, then remove 1. 2 and 3 also same, and it is clear.
but. if i change some value and try to remove. then. removed it from below.

i don't know it is bug of lit or html or something..

of course it can be solve by another way with additional code but i think it is not natural.

https://github.com/lit/lit-element/issues/807
https://stackoverflow.com/a/59381119/12365658

Steps to Reproduce

1. Write this code
2. change value.
3. click remove event.

import { LitElement, html } from 'lit';
import { customElement, property } from 'lit/decorators.js';

@customElement('test-container')
export class TestContainer extends LitElement {
  testItems = [
    {innerId: 1, value: 1},
    {innerId: 2, value: 2},
    {innerId: 3, value: 3}
  ]

  render(){

    const items = []
    for(const item of this.testItems){
      items.push(this.renderItem(item.innerId, item.value));
    }

    return html`<div>${items}</div>`;
  }

  renderItem(id: number, value: number){
    return html`<test-item @remove=${this.clickRemoveItem} innerId=${id} value=${value}></test-item>`
  }

  clickRemoveItem(e: any){
    const remove_id = e.detail.innerId;
    for(let i=0; i < this.testItems.length; i++) {
      if(this.testItems[i].innerId == remove_id) {
        this.testItems.splice(i, 1);
        break;
      }
    }
    this.requestUpdate();
  }
}

@customElement('test-item')
export class TestItemContainer extends LitElement{

  @property()
  innerId = "";

  @property()
  value = "";

  clickRemove(){
    this.dispatchEvent(new CustomEvent("remove", {detail: {innerId: this.innerId}, bubbles: true, composed: true}))
  }

  render(){
    const countries_template:any = [];

    return html`
      <div @click=${this.clickRemove}>Remove</div>
      <input type="text" value=${this.value}>
    `
  }
}

4. See this output...

Live Reproduction Link

https://stackblitz.com/edit/lit-html

Expected Results

Actual Results

Browsers Affected

• Chrome
• Firefox
• Edge
• Safari 11
• Safari 10
• IE 11

Start with the TypeScript reproduction in the issue and the linked StackBlitz example, then review the linked lit-element issue and Stack Overflow answer. The issue does not name a documentation file or provide expected and actual results; it would be done when the appropriate repeat() guidance and its intended behavior are clearly documented.