Update:

If I add the line

  undef %{$coord};
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once I'm finished with $coord, the leak slows down but does not stop. I probably need to dig into the reference a little deeper and undef pieces of it individually.

-Phil

Addendum: It turns out the structure doesn't go any deeper. Here's what Data::Dump returned:

{ bottom => 901, left => 432, right => 1182, top => 302 }
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