I'm not sure how much of this can be considered a bug, but the fact that it looks strange is a fact. The portals are displayed correctly on the front side of the capes, and for some reason they are shifted by 1 pixel on the reverse side, which does not look good. Fix it, please, because it hurts to watch...
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We're tracking this issue in MCPE-191549, so this ticket is being resolved and linked as a duplicate.
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