Show posts based on user preference in wordpress

Code.php

<?php

add_action( 'show_user_profile', 'extra_fields' );
add_action( 'edit_user_profile', 'extra_fields' );
add_action( 'personal_options_update', 'save_fields' );
add_action( 'edit_user_profile_update', 'save_fields' );
add_action( 'pre_get_posts', 'exclude_category' );
 
function extra_fields($user) {
	$pref_cat = explode( ',', get_user_meta( $user->ID, 'pref_cat', true ) );
	?>
	<h3><?php _e("Extra profile information", "DOMAIN"); /*DOMAIN = Lang domain for l10n (optional)*/ ?></h3>
	<table class="form-table">
		<tbody>
			<tr>
				<th><?php _e("Your preferred categories", "DOMAIN"); /*DOMAIN = Lang domain for l10n (optional)*/ ?></th>
				<td>
					<?php
						$categories = get_categories( array( 'type' => 'post' ) );
						foreach( $categories as $cat ){
							?>
							<label><input <?php echo in_array( $cat->term_id, $pref_cat ) ? 'checked' : '' ?> type="checkbox" name="pref_cat[]" value="<?php echo $cat->term_id ?>"> <?php echo $cat->name ?></label>
							<?php
						}
					?>
				</select>
			</tr>
		</tbody>
	</table>
<?php
}
 
function save_fields( $user_id ) {
	if ( !current_user_can( 'edit_user', $user_id ) ) { return false; } //Checking if the current user has ability to edit the user profile information
	update_user_meta( $user_id, 'pref_cat', implode( ',', $_POST['pref_cat'] ) );
}

function exclude_category( $query ) {
	if( is_user_logged_in() ) {
		$current_user = wp_get_current_user();
		if ( $query->is_home() && $query->is_main_query() ) {
			$query->set( 'cat', get_user_meta( $current_user->ID, 'pref_cat', true )  );
		}
	}
}