Featured image alignment not working with child theme

Hello!

I am using the "marketer" generatepress theme. When working on the site layout i found out that using a custom excerpt removes the "read more" button. The solution to this was to have a child theme with the following in functions.php:

add_filter( 'wp_trim_excerpt', 'tu_excerpt_metabox_more' );
function tu_excerpt_metabox_more( $excerpt ) {
	$output = $excerpt;
	if ( has_excerpt() ) {
		$output = sprintf( '%1$s <p class="read-more-container"><a class="button" href="%2$s">Read more</a></p>',
			$excerpt,
			get_permalink()
		);
	}	
	return $output;
}

However, after applying this, my posts featured images are now showing full size instead of the scaled down 300px width it was before. No matter what I select for "left, right, or centered" it shows the fullsize image and then the excerpt below it.