In Joomla 3.10 the button does not appear, no matter if JCE or TinyMCE.

Dear sir,

I fixed the issue, please check your site again.
For Joomla 3.10 only, the solution is:
in the file: plugins\system\ytshortcodes\ytshortcodes.php
Please find:
if($version->RELEASE < '3.5' ){
$page = str_replace('<div id="editor-xtd-buttons" class="btn-toolbar pull-left">', '<div id="editor-xtd-buttons" class="btn-toolbar pull-left">' . $button, $page);
}else
{
$page = str_replace('<div class="toggle-editor btn-toolbar pull-right clearfix">', $button.'<div class="toggle-editor btn-toolbar pull-right clearfix">', $page);
}

Edit to:
$app = JFactory::getApplication();
$editor = $app->getCfg('editor');
if($editor == "tinymce")
{
$page = str_replace('<div class="toggle-editor btn-toolbar pull-right clearfix">','<div id="editor-xtd-buttons" class="btn-toolbar pull-left">'. $button.'</div><div class="toggle-editor btn-toolbar pull-right clearfix">', $page);
}else{
$page = str_replace('<div id="editor-xtd-buttons" class="btn-toolbar pull-left">', '<div id="editor-xtd-buttons" class="btn-toolbar pull-left">' . $button, $page);
}

If it's the code:
if($version->RELEASE < '3.5' ){
$page = str_replace('<div id="editor-xtd-buttons" class="btn-toolbar pull-left">', '<div id="editor-xtd-buttons" class="btn-toolbar pull-left">' . $button, $page);
}else
{
$app = JFactory::getApplication();
$editor = $app->getCfg('editor');
if($editor == "tinymce")
{
$page = str_replace('<div class="toggle-editor btn-toolbar pull-right clearfix">','<div id="editor-xtd-buttons" class="btn-toolbar pull-left">'. $button.'</div><div class="toggle-editor btn-toolbar pull-right clearfix">', $page);
}else{
$page = str_replace('<div id="editor-xtd-buttons" class="btn-toolbar pull-left">', '<div id="editor-xtd-buttons" class="btn-toolbar pull-left">' . $button, $page);
}
}
please edit to:
$app = JFactory::getApplication();
$editor = $app->getCfg('editor');
if($editor == "tinymce")
{
$page = str_replace('<div class="toggle-editor btn-toolbar pull-right clearfix">','<div id="editor-xtd-buttons" class="btn-toolbar pull-left">'. $button.'</div><div class="toggle-editor btn-toolbar pull-right clearfix">', $page);
}else{
$page = str_replace('<div id="editor-xtd-buttons" class="btn-toolbar pull-left">', '<div id="editor-xtd-buttons" class="btn-toolbar pull-left">' . $button, $page);
}

Thanks