Hi there,
try this snippet instead:
add_filter('generate_excerpt_more_output', function($output){
return sprintf(
' ... <a title="%1$s" class="read-more" href="%2$s" aria-label="%4$s">%3$s %1$s</a>',
the_title_attribute( 'echo=0' ),
esc_url( get_permalink( get_the_ID() ) ),
__( 'Read ', 'generatepress' ),
sprintf(
/* translators: Aria-label describing the read more button */
_x( 'More on %s', 'more on post title', 'generatepress' ),
the_title_attribute( 'echo=0' )
)
);
}, 10);