use warnings;
use strict;

while (<DATA>) 
{
    process_record() if /\@user_info_start/;
}

sub process_record
{
  my $line;
  print $line while (defined ($line =<DATA>) and $line !~ /\@user_info_end/);
  print "\n";
}   
   

=Prints
xxxx*@Title         : Mr
xxxx*@Username   : xxxxx
xxxx*@Filetype    : txt
xxxx*@Version       : 0001
xxxx*@Create_Date       : 20190407
xxxx*@Product       : xxxx

xxxx*@Title         : Mr
xxxx*@Username   : yy
xxxx*@Filetype    : txt
xxxx*@Version       : 0005
xxxx*@Create_Date       : 43
xxxx*@Product       : xxxx

=cut

__DATA__
xxxxxxxxxxx
xxxx*@user_info_start
xxxx*@Title         : Mr
xxxx*@Username   : xxxxx
xxxx*@Filetype    : txt
xxxx*@Version       : 0001
xxxx*@Create_Date       : 20190407
xxxx*@Product       : xxxx
xxxx*@user_info_end
d987sd66bd
xxxxxxxxxxxxxxxxxxxxxxxxxxxx
xxxxxxxxxxx
xxxx*@user_info_start
xxxx*@Title         : Mr
xxxx*@Username   : yy
xxxx*@Filetype    : txt
xxxx*@Version       : 0005
xxxx*@Create_Date       : 43
xxxx*@Product       : xxxx
xxxx*@user_info_end
somebus here or blank lines? whatever
xxxxxxxxxxxxxxxxxxxxxxxxxxxx