Tell SearchWP to ignore any post(s) with a specified meta key value

searchwp-customizations.php

<?php

// Tell SearchWP to exclude any posts with a my_meta_key
// value of 'meta value 1', 'meta value 2', or 'meta value 3'.
add_filter( 'searchwp\post__not_in', function( $ids ) {
	return array_unique( array_merge( $ids, get_posts( [
		'fields'     => 'ids',
		'nopaging'   => true,
		'post_type'  => 'any',
		'meta_query' => [ [
			'key'     => 'my_meta_key',
			'value'   => [ 'meta value 1', 'meta value 2', 'meta value 3', ],
			'compare' => 'IN',
		], ],
	] ) ) );
}, 20, 2 );