Source

File: wp-includes/class-wp-customize-manager.php

public function stop_previewing_theme() {
		if ( ! $this->is_preview() ) {
			return;
		}

		$this->previewing = false;

		if ( ! $this->is_theme_active() ) {
			remove_filter( 'template', array( $this, 'get_template' ) );
			remove_filter( 'stylesheet', array( $this, 'get_stylesheet' ) );
			remove_filter( 'pre_option_current_theme', array( $this, 'current_theme' ) );

			// @link: https://core.trac.wordpress.org/ticket/20027
			remove_filter( 'pre_option_stylesheet', array( $this, 'get_stylesheet' ) );
			remove_filter( 'pre_option_template', array( $this, 'get_template' ) );

			// Handle custom theme roots.
			remove_filter( 'pre_option_stylesheet_root', array( $this, 'get_stylesheet_root' ) );
			remove_filter( 'pre_option_template_root', array( $this, 'get_template_root' ) );
		}

		/**
		 * Fires once the Customizer theme preview has stopped.
		 *
		 * @since 3.4.0
		 *
		 * @param WP_Customize_Manager $this WP_Customize_Manager instance.
		 */
		do_action( 'stop_previewing_theme', $this );
	}