ESP cannot read the sensor values in the 8 channels through xiao's UART😢

I use two board: ESP32 DEVIKIT V1 and Seeeduino XIAO.
XIAO is arduino hardware, code:

void setup()
{
  analogReadResolution(16);
  SerialUSB.begin(9600);
  Serial1.begin(1000000);
  while (!Serial1){};
}
// arduino设置16采样位,采样8通道的传感器数值
// ESP通过uart接收采样数据,然后传到蓝牙的TX参数发送notify

void loop()
{
  int i;
  unsigned long elsp = millis();
  for (i = 0; i < 50; i++)
  {

    // read the input on analog pin 0:
    Serial1.printf("%d:%d:%d:%d:%d:%d:%d:%d", analogRead(A0), analogRead(A1), analogRead(A2), analogRead(A3), analogRead(A4), analogRead(A5),analogRead(A6),analogRead(A7));
    Serial1.println();
  }

  Serial1.printf("XIAO Time: %d \n", millis() - elsp);
  Serial1.println(Serial1.availableForWrite());
  SerialUSB.println(millis() - elsp);
  SerialUSB.println("waiting...");
  delay(5000);
}

ESP32 code:

void setup()
{
  Serial.begin(1000000);
  Serial1.begin(1000000, SERIAL_8N1, 16, 17);

  while (!Serial)
  {
  };
  Serial.println("Set Serial1 ok!");
}
String xiao = "";
void loop()
{
  unsigned long elsp = millis();
  if (Serial1.available() > 0)
  {
    if (Serial1.peek() != '\n')
    {
      xiao += (char)Serial1.read();
    }
    else
    {
      Serial1.read();
      Serial.println(xiao);
      xiao = "";
    }
  }
}

Only by reducing arduino’s Analogread () to 6 can ESP read the value of the 6-channel SENSOR of UART:

image

I tried adding program headers to amplify the buffer:

#define SERIAL_TX_BUFFER_SIZE 4096
#define SERIAL_RX_BUFFER_SIZE 4096

But the ESP couldn’t receive it and could only read the 6-channel sensor, while the Arduino serial computer could read the 8-channel sensor

Is it UART restriction or something? How can I solve the problem?

Can someone help me? :cry:I don’t know why ESP32 not receive a string of eight five-character characters plus seven ‘:’