Yes, that's the one I was talking about, and yes, you are right. Trying to correct along another line that leads me to another nice solution:

my @field = split /,/, $text;

my @even = @field[ map $_ * 2,     0 .. ( @field / 2 ) - 1 ];
my @odd  = @field[ map $_ * 2 + 1, 0 .. ( @field / 2 ) - 1 ];
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(Despite the two maps, it only iterates once — a half-iteration in each of them.)