iamvagl

const input = document.getElementById('input');
			input.addEventListener('input', event => {
			    const value = event.target.value.trim().toLowerCase().toString();
			    document.querySelectorAll('.ul li').forEach(node => {
			        if (value !== '' && !node.textContent.toLowerCase().includes(value)) {
			        	node.classList.add('hide')
			        } else {
			        	node.classList.remove('hide');
			        }
			        if (value == '') {
			        	node.classList.add('hide');
			        }
			    });
			});

<div class="search input-group" >
			<input type="search" name="" class="input__form" id="input" placeholder="Поиск товаров..">
			<ul class="ul list-group">
				<li id="item1" class="item4 list-group-item hide">TWS Apple Airpods Pro 1</li>
				<li id="item1" class="item4 list-group-item hide">TWS Apple Airpods Pro 2</li>
				<li id="item1" class="item4 list-group-item hide">TWS Apple Airpods Pro 3</li>
			</ul>
		</div>