use strict;
use warnings;
use Data::Dumper;

my $path = '/.snapshots123/yabsm/root/hourly/day=2021_03_04,time=21:20';

my @nums = $path =~ m{/day=(\d\d\d\d)_(\d\d)_(\d\d),time=(\d\d):(\d\d)$};
print Dumper( \@nums );