Remove the space before the [...] before Read More link

Are you talking about the single space between the excerpt content and the "..."?

Yes thats correct

Try this php below:

add_action( 'after_setup_theme','tu_remove_read_more' );
function tu_remove_read_more() {
    remove_filter( 'excerpt_more', 'generate_blog_excerpt_more', 99 );
}

add_filter( 'excerpt_more', 'tu_blog_excerpt_more', 99 );
function tu_blog_excerpt_more( $more ) {
    if ( ! function_exists( 'generate_blog_get_defaults' ) )
        return;

    $generate_settings = wp_parse_args( 
        get_option( 'generate_blog_settings', array() ), 
        generate_blog_get_defaults() 
    );
	
    // If empty, return
    if ( '' == $generate_settings['read_more'] )
        return;
		
    return '... <a title="' . esc_attr( get_the_title() ) . '" class="read-more" href="'. esc_url( get_permalink( get_the_ID() ) ) . '">' . $generate_settings['read_more'] . '</a>';
}

Adding php: https://docs.generatepress.com/article/adding-php/

Let me know.