Source

File: wp-includes/rest-api/fields/class-wp-rest-meta-fields.php

protected function is_meta_value_same_as_stored_value( $meta_key, $subtype, $stored_value, $user_value ) {
		$args      = $this->get_registered_fields()[ $meta_key ];
		$sanitized = sanitize_meta( $meta_key, $user_value, $this->get_meta_type(), $subtype );

		if ( in_array( $args['type'], array( 'string', 'number', 'integer', 'boolean' ), true ) ) {
			// The return value of get_metadata will always be a string for scalar types.
			$sanitized = (string) $sanitized;
		}

		return $sanitized === $stored_value;
	}