$ perl -Mstrict -MRegexp::Common=time -MDateTime::Format::ISO8601 -wE '
my $str = "2018-03-01T110601Z";
say "DateTime::Format: ", eval { my $dt = DateTime::Format::ISO8601->parse_datetime($str) } ? "valid" : "not valid: $@";
say "Regexp::Common: ", $str =~ /$RE{time}{iso}/ ? "valid" : "not valid";
'

DateTime::Format: not valid: Invalid date format: 2018-03-01T110601Z at -e line 3.
	eval {...} called at -e line 3

Regexp::Common: valid

##</code><code>##

$ perl -Mstrict -MRegexp::Common=time -MDateTime::Format::ISO8601 -wE '
my $str = "2018-03-01T11:06:01Z";
say "DateTime::Format: ", eval { my $dt = DateTime::Format::ISO8601->parse_datetime($str) } ? "valid" : "not valid: $@";
say "Regexp::Common: ", $str =~ /$RE{time}{iso}/ ? "valid" : "not valid";
'

DateTime::Format: valid
Regexp::Common: valid