Guessing...

#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11142528
use warnings;

my @AoH = do
  {
  local $/ = "objet => fin\n";
  map { s/^objet => .*\n//gm; +{ split /"?\n(?:\.{3}\n)?| => "?/} } <D
+ATA>;
  };

use Data::Dump 'dd'; dd \@AoH;

__DATA__
objet => debut
index => 1
a => "premiere valeur"
b => 'better example required"
z => "dernier mot"
objet => fin
objet => debut
index => 77
a => "autre valeur"
y => 'better example required"
z => "aurai-je le dernier mot ?"
objet => fin
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Outputs:

[
  {
    a => "premiere valeur",
    b => "'better example required",
    index => 1,
    z => "dernier mot",
  },
  {
    a => "autre valeur",
    index => 77,
    y => "'better example required",
    z => "aurai-je le dernier mot ?",
  },
]
[download]