una/modules/boonex/messenger/template/mobile-menu-button.html

<div class="block md:hidden bx-messenger-history-block-header-menu-back">
    <a href="javascript:void(0);" onclick="oNavMenu.showHistoryPanel()">
        <svg xmlns="http://www.w3.org/2000/svg" fill="none" viewBox="0 0 24 24" stroke-width="1.5" stroke="currentColor" class="w-8 h-8">
            <path stroke-linecap="round" stroke-linejoin="round" d="M15.75 19.5L8.25 12l7.5-7.5" />
        </svg>
    </a>
</div>