Do macros not allow comma separated definitions in their arguments?

Question

I've found a interesting code snippet that works pretty strange

#include <iostream>
#include <cstdio>
#define DEBUG_CMD(cmd)                                                                             \
    do {                                                                                           \
        cmd;                                                                                       \
    } while (false)

using namespace std;

int main()
{
    cout<<"Hello World";
    DEBUG_CMD({
        int x = 1;
        int y = 1;
        //int x= 1, y =1; // enable this and comment two lines above will yield an error
        printf("x: %d y: %d\n", x, y);
    });

    return 0;
}

when I define x, y seperately, the code can run. but when I define x y in the same statement sperated by comma, the compiler complains about the syntax error.

main.cpp:26:6: error: macro "DEBUG_CMD" passed 2 arguments, but takes just 1
     });
      ^
main.cpp: In function ‘int main()’:
main.cpp:21:5: error: ‘DEBUG_CMD’ was not declared in this scope
     DEBUG_CMD({
     ^~~~~~~~~

I wonder what's happening here.

TIPS: you can compile it at https://onlinegdb.com/ryUuyZEmO and it also gives you the same error.