It looks like a normal end portal with no end portal frames. How to make, can only be made in creative, make a normal end portal, add all the eyes, add end portal frames on the corners to make a square, if you want to you could add eyes on the corners but do not break corners now, next break one all of the non corner ones and it will still be on, now break the corners and done, the portal is still on with no frames
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We're tracking this issue in MCPE-134032, so this ticket is being resolved and linked as a duplicate.
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