gdb-add-index contains:

$GDB --batch -nx -iex 'set auto-load no' \
    -iex 'set debuginfod enabled off' \
    -ex "file $file" -ex "save gdb-index $dwarf5 $dir"

So it always disables debuginfod.
But gdb/debuginfod-support.c has:

/* Set callback for "set debuginfod enabled".  */ 
 
static void 
set_debuginfod_enabled (const char *value) 
{ 
#if defined(HAVE_LIBDEBUGINFOD) 
  debuginfod_enabled = value; 
#else 
  error (NO_IMPL); 
#endif 
}

So when not compiled against libdebuginfod that will always generate a error on stderr.

This causes some testcase in dwz to FAIL, because any output to stderr is seen as failure.

It also makes package build logs (if they use gdb-add-index) somewhat noisy.