pascalwp

Its not a browser cache problem.

I found the solution

add_action( 'wp', 'addtx_homeheader' );
function addtx_homeheader()
{

if(is_front_page())
{
add_action('wp_head', '_set_metatag');
}
}

function _set_metatag()
{
$output = '';
$output .= '<meta property="og:type" content="MYPLUGINTEST" />';
echo $output;
}

No
If I use is_front_page() or is_home not working by using is in a custom plugin.

But this works when I put that directly in header.php

if(is_front_page())
{
$output = '';
$output .= '<meta property="og:type" content="website" />';
echo $output;
}

Why this is not working if a create it in a plugin?

if(is_home())
{
add_action('wp_head', '_set_metatag');
}

function _set_metatag()
{
$output = '';
$output .= '<meta property="og:type" content="website" />';
$output .= '<meta property="og:url" content="https://website.com" />';
$output .= '<meta property="og:title" content="websitetitle" />';
echo $output;
}

Note : I tested is_home() and is_front_page()