I created a function to write with Firebase, but there is a problem with implementing the search function

I made a writing function with Firebase, but when I search for the title, if it’s ice cream, it comes out when I search for ice cream, but it doesn’t come out when I search for cream I’ve tried a plug-in called searchflex, but it doesn’t work.
I asked the method I ordered on the Internet and AI, but I can’t do what I was told, so I have a question left.

import { db } from './firebaseConfig.js';
import { collection, getDocs } from 'firebase/firestore';
import { PostListManager } from './PostListManager.js';

export async function setupSearch() {
    const searchButton = document.getElementById('searchBtn');
    const searchInput = document.getElementById('searchInput');
    const resultsContainer = document.getElementById('results');

    const postListManager = new PostListManager('results');


    async function loadData() {
        try {
            const querySnapshot = await getDocs(collection(db, 'posts'));
            const posts = querySnapshot.docs.map(doc => ({
                id: doc.id,
                ...doc.data()
            }));
            return posts;
        } catch (error) {
            console.error('Error loading data from Firestore:', error);
            return [];
        }
    }

  
    async function performSearch() {
        const searchText = searchInput.value.trim().toLowerCase();
        if (searchText === "") {
            console.log("Empty search text.");
            return;
        }

        try {
            const posts = await loadData();
            const filteredPosts = posts.filter(post => {
                const titleMatch = post.title && post.title.toLowerCase().includes(searchText);
                const descriptionMatch = post.description && post.description.toLowerCase().includes(searchText);
                const contentMatch = post.content && post.content.toLowerCase().includes(searchText);
                return titleMatch || descriptionMatch || contentMatch;
            });

            if (filteredPosts.length === 0) {
                console.log('No matching documents found.');
            } else {
                console.log(`Found ${filteredPosts.length} matching documents.`);
            }

            postListManager.renderPosts(filteredPosts, false);
        } catch (error) {
            console.error('Error during search:', error);
        }
    }

    // 검색 버튼 클릭 이벤트
    searchButton.addEventListener('click', performSearch);

    // 엔터 키 입력 시 검색 수행
    searchInput.addEventListener('keypress', (e) => {
        if (e.key === 'Enter') {
            performSearch();
        }
    });
}