sends floating values from an arduino to a rpi via i2c

RxRpi.py

import struct
import smbus
import time

# for RPI version 1, use "bus = smbus.SMBus(0)"
bus = smbus.SMBus(1)

# This is the address we setup in the Arduino Program
address = 0x04

def get_data():
    return bus.read_i2c_block_data(address, 0, 8);

def get_float(data, index):
    bytes = data[4*index:(index*4)+4]
    return struct.unpack('f', "".join(map(chr, bytes)))[0]
    #return
while True:

        data = get_data()
        print(get_float(data, 0))
        print(get_float(data, 1))
        print(get_float(data, 2))
        print("attend")
        time.sleep(3);

TxArduino.ino

#include <Wire.h>

#define SLAVE_ADDRESS 0x04

#define FLOATS_SENT 3

float temperature = 10.5;
float luminosity = 5.0;
float batterie = 49.4;

float data[FLOATS_SENT];

void setup() {
    pinMode(13, OUTPUT);
    Serial.begin(9600);
    
    data[0] = temperature;
    data[1] = luminosity;
    data[2] = batterie;
    
    // initialize i2c as slave
    Wire.begin(SLAVE_ADDRESS);

    // define callbacks for i2c communication
    Wire.onRequest(sendData);
}

void loop() {
    delay(100);
}

 void sendData(){Wire.write((byte*) &data, FLOATS_SENT*sizeof(float));}

Here are the two code I used to send three floating values from an Arduino to a Raspberry connected by the i2c bus.
For two floating it works very well but when I add the third, that I try to display by the print(get_float(data, 2))

I receive this error message on the terminal of the raspberry

return struct.unpack ('f', "" .join (map (chr, bytes))) [0] struct.error: unpack requires a string argument of length 4

Any ideas please ??