Solved sendBlocks error

This is so strange... Your method worked! (I mean @Muqsit 's method )

Problem solved, you can use these methods if you have the same problem

PHP:

$pk = new \pocketmine\network\mcpe\protocol\UpdateBlockPacket();
$pk->blockId = 54;
$pk->blockData = 0;
$pk->x = (int) $player->x;
$pk->y = (int) $player->y - 2;
$pk->z = (int) $player->z;
$pk->flags = UpdateBlockPacket::FLAG_NONE;
$player->dataPacket($pk);

and

PHP:

$block = Block::get(54);
$block->x = $player->getFloorX();
$block->y = $player->getFloorY() -2;
$block->z = $player->getFloorZ();
$block->level = $player->level;
$player->level->sendBlocks([$player],[$block]);

Thank you all for the help!