Chat::isUserKickedFromChat

static function isUserKickedFromChat($chatId, $userId = 0) : bool
{
	if ($userId === 0)
	{
		$userId = BitrixImCommon::getUserId();
	}

	if (!$userId)
	{
		return false;
	}

	$result = BlockUserTable::getList(
		[
			'select' => ["ID"],
			'filter' => [
				'=USER_ID' => $userId,
				'=CHAT_ID' => $chatId
			]
		]
	)->fetch();

	return (bool)$result['ID'];
}