Passing array to function changes function 'sizeof(array)' [duplicate]

EDIT: I believe this question is different from How do I determine the size of my array in C?, because that link discusses how to use sizeof(nlist)) / sizeof(nlist[0]) to determine the number of items in an array.

My question is asking why that stops working after the array has been passed to a function.

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I'm new to ansi C, coming from Python.

I have a function that parses an int array. The iteration through the array is dependent on sizeof(nlist)) / sizeof(nlist[0]) to determine the size of the array.

However, while this works in main(), it fails when the array is passed to a function.

In main file

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include "arrayTools.h"

int main() {

    // Fill with data for testing
    int nlist[500];
    for (int i=1; i<501; i++ ) {
        nlist[i] = i;
    }

    // This successfully iterates through all 500 items
    for( size_t i = 1; i <= (sizeof(nlist)) / sizeof(nlist[0]); i++)
    {   
        printf(isItemInIntArray(i, nlist) ? "true\n" : "false\n");
    }

arrayTools.h

#include <stdbool.h>
#include <stdlib.h>

bool isItemInIntArray(int value, int arr[]){
    // This only iterates twice (i = 1, then i = 2) and then ends
    for( size_t i = 1; i <= (sizeof(arr)) / sizeof(arr[0]); i++) {
        if (value == arr[i]) { return true; }
    }
    return false;
}