a not so perfect solution , but might work

#!/usr/bin/perl
use strict;
use warnings;

my @array;
my $PreviousLines = 4;
while (<DATA>) {
    chomp;    
    if (/xyz/) {
        print join "\n", @array;
        print "\n\n";        
    }else{
        push @array, $_;
        if (@array > $PreviousLines ) {
            # delete first element 
            splice @array, 0,1;
        }
        
    }    
}
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