It’s from one of the libraries I’m using.  The first time I use it (see code below) it displays the image and caption.  So I think you’re right, somewhere in the pipeline my image is getting bloated.
trn_ds = CaptioningData(DEBUG_TRAIN, data[-data['train']], vocab) # debug code uses only validation data
val_ds = CaptioningData(DEBUG_TRAIN, data[-data['train']], vocab)

image, target, caption = trn_ds.choose()
show(image, title=caption, sz=5); print(target)