Why does XIAO abnormal output when reading multiple ADCs?

[allrobot]

problem

If the loop runs only one or two simulated pin and uses a filter, it will output normally (0~30), but using three or more will output an exception (1000~20000).

#include "EMGFilters.h"
const int SensorInputPin[] = {A0, A1, A2, A3, A4, A5};
EMGFilters myFilter[6];
SAMPLE_FREQUENCY sampleRate = SAMPLE_FREQ_500HZ;
NOTCH_FREQUENCY humFreq = NOTCH_FREQ_50HZ;

void setup()
{

    for (int i = 0; i < 6; i++)
    {
        myFilter[i].init(sampleRate, humFreq, true, true, true);
    }
    Serial.begin(115200);
}
void loop()
{
    int x[6] = {0};

    for (int index = 0; index < 3; index++)
    {
        x[index] = myFilter[index].update(analogRead(SensorInputPin[index]));
            delayMicroseconds(500);
    }

}

output:

There is no problem with the filter itself, but with the ADC reading value

filter code: https://github.com/oymotion/EMGFilters/blob/master/EMGFilters.cpp

I guess XIAO’s filtering calculations take time, but I tried adding 500 microseconds, 2 milliseconds, and 5 milliseconds, and they didn’t good work.

So I guess XIAO ADC pins exits a problem.

I try to do:

...etc
void loop()
{
    Serial.println(myFilter[0].update(analogRead(SensorInputPin[per ADC pin])));
}

XIAO read the output of each pin one by one, and they output normally.

• Why does using pins that continuously read from 0 to 5 cause problems?