Add relevance weight to a single SearchWP Source

searchwp-customizations.php

<?php

// Add relevance weight to a single SearchWP Source.
add_filter( 'searchwp\query\mods', function( $mods ) {
	global $wpdb;

	$mod = new \SearchWP\Mod();
	$mod->weight( "IF(s.source = 'user', 9999999, 0)" );

  $mods[] = $mod;

	return $mods;
} );