Why do i get warning with model lifecycle deprecated?

in Ember 3.15

I generated model and defined attributes. when I execute findRecord(), I got warning with model lifecyclle deprecated.

I didn’t use model lifycycle event;

What is the reason?

my model source

import Model, { attr, belongsTo } from '@ember-data/model';

export default class UserModel extends Model {
	@attr('string') nickname;
	@attr('string') email;
	@attr('number') state;
	@attr('string') auth;
	@attr('string') google;
	@attr('string') kakao;

and application adapter

import RESTAdapter from '@ember-data/adapter/rest';
import config from '../config/environment';
import { inject as service } from '@ember/service';
import { computed } from '@ember/object';

export default class ApplicationAdapter extends RESTAdapter {
  @service utils;
  @service session;

  host = config.serverHost;
  namespace = `api/${config.appid}`;

  get headers() {
    return { 'Authorization' : this.session.getCookie('happykoo-tmp') }


and application serializer

export { default } from '@ember-data/serializer/rest';