$baseURL ci 4 and ci3

on ci3, $baseURL i setup as http://localhost/ci3/ , it worked correctly with end slash
but on ci4, $baseURL = 'http://localhost/ci4/' on .env and Config/App.php it come out with out end slash -> http://localhost/ci4
am i missing something or is this normal? 

on ci3, $baseURL i setup as http://localhost/ci3/ , it worked correctly with end slash
but on ci4, $baseURL = 'http://localhost/ci4/' on .env and Config/App.php it come out with out end slash -> http://localhost/ci4
am i missing something or is this normal? 

Where "it come out with out end slash" ?

ci-phpunit-test | CodeIgniter Testing Guide | CodeIgniter 3 to 4 Upgrade Helper

on ci3, $baseURL i setup as http://localhost/ci3/ , it worked correctly with end slash
but on ci4, $baseURL = 'http://localhost/ci4/' on .env and Config/App.php it come out with out end slash -> http://localhost/ci4
am i missing something or is this normal? 

Where "it come out with out end slash" ?

on CI3
$config['base_url'] = 'http://localhost/ci3/'; if you do <?php echo base_url(); ?>, output is http://localhost/ci3/
$config['base_url'] = 'http://localhost/ci3'; if you do <?php echo base_url(); ?>, output is http://localhost/ci3
CI4
app.baseURL = 'http://localhost/ion/', or app.baseURL = 'http://localhost/ion if you do <?php echo base_url(); ?>, output is always http://localhost/ion
no end slash

I don't know why but it seems it is a specification of CI4's base_url().

ci-phpunit-test | CodeIgniter Testing Guide | CodeIgniter 3 to 4 Upgrade Helper