Your problem has nothing to do with either UNIVERSAL or AUTOLOAD. You're seeing that behaviour because your AUTOLOAD was built in package main. Examine the following:

sub Test1::print_context {
   print(__PACKAGE__, "\n");
}

{
   package Test2;
   sub print_context {
      print(__PACKAGE__, "\n");
   }
}

Test1::print_context();  # main
Test2::print_context();  # Test2
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Fixed code:

#!/usr/bin/perl -w

{
   package UNIVERSAL;

   use Carp;

   sub AUTOLOAD {
      carp "foo";
   }
}

bar();
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