Though I think that can lead to subtle issues as well, such as losing the class when doing assignment.

Uhm, you lose the type of scalar as well if you assign to the variable that holds it.

my $a = 'Foo'; # $a isa Str now
$a = 42;       # $a isa Int now
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You're just used to dealing with it with scalars

my @list = CustomList.new();
@list = @other_list; # you lose @list's type as well

# assignment that preservers the type has to
# assign to the contents, not the container:
@list[*] = @other_list;
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