It's a graphic element used in magazines and newspapers at the end of an article, to let the reader know the text ends in that page. It can be the magazine logo, or a variant of it, or just an abstract shape.
2 Answers
As the tombstone character ∎ has been used in this capacity very regularly, I have seen these end marks referred to by that name.
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Support for this answer: en.wikipedia.org/wiki/Tombstone_(typography) and en.wikipedia.org/wiki/Q.E.D.– IdeogramOct 30, 2020 at 9:35
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