I am unable to reproduce your problem. I'm not on FreeBSD, however.

$ perl -v | head -3

This is perl 5, version 30, subversion 0 (v5.30.0) built for x86_64-li
+nux

$ perl -T -MDate::Manip -E 'say $Date::Manip::VERSION;'
6.82
$
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If you could provide an SSCCE then perhaps it would help to show where the problem really lies.

Update: following parv's uncovering the likely culprit I confirm that this reproduces the error for me too:

$ ENV=foo perl -T -MDate::Manip -E 'say $Date::Manip::VERSION;'
ERROR LOADING MODULE: Date::Manip::DM6 at /path/to/perlbrew/perls/perl
+-5.30.0/lib/site_perl/5.30.0/Date/Manip.pm line 35.
Compilation failed in require.
BEGIN failed--compilation aborted.
$
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