Another splice method with two joins, one in a map, and an on-the-fly subroutine.

knoppix@Microknoppix:~$ perl -E '
> @arr = qw{
>    name
>    John
>    number
>    7
>    status
>    unknown
>    };
> $str =
>    join q{&},
>       map { join q{=}, @$_ }
>       sub {
>           push @ret, [ splice @_, 0, 2 ] while @_;
>           return @ret;
>           }->( @arr );
> say $str;'
name=John&number=7&status=unknown
knoppix@Microknoppix:~$
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