This seems like it's a bad thing, because writing use v5.40; on a script doesn't let you override the true & false builtins afterwards by using something like use Mojo::JSON qw/ true false /;, nor with no builtin qw/ true false /, so we're all stuck with v5.40's builtin boolean values, and maybe you should consider this.

DBD::Pg thinks false is an empty string, and PostgreSQL returns an error:

My example script:

#!/usr/bin/env perl

use v5.40;
use FindBin '$RealBin';
use lib "$RealBin/local/lib/perl5";

use DBI;

my $dbh = DBI->connect('dbi:Pg:dbname=dbname;host=127.0.0.1', 'user', 'pass', {AutoCommit => 1});

$dbh->do('INSERT INTO "foo" ("value") VALUES (?)', undef, false);

Output:

DBD::Pg::db do failed: ERROR:  invalid input syntax for type boolean: ""
CONTEXT:  unnamed portal parameter $1 = '' at ./true_false.pl line 11.