I can definitely hear the similarity, but it's a pretty simple beat. I'm sure there are plenty of other artists out there who have coincidentally used something similar to Dark Horse and this song too. Doesn't smell like a rip off to me, not like Luke's blatant Timber exposé earlier this week.
I don't see this holding up. The instrumentals have very little in common and its really quite common that whenever a song is a big hit, SOMEONE will come crawling out of the woodwork to claim plagarism.
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