GP adds title tag support using the WP core function ie.
add_theme_support( 'title-tag' );
WP then hooks in the title tag for us, but we don’t interfere with what is outut – we leave that to the core defaults. Which for a single post type returns this as an example ( taken from this topic ):
<title>Title tag with Quotes - GeneratePress</title>
As you have
"" quotes and a
| pipe character in yours means there is some other function that is changing that.
If its no Rankmath, then do you have any other plugins or functions that intefere with the meta ?