Have you checked out Caribbean Beach resort ? We had purchased ours a couple months ago there and they had them in both the Old Port Royale's Centertown Market and Calypso Trader Post store.
I don't think the Skyliner mugs have existed since the parks re-opened. My sister & BIL got them when they visited in February 2020, but I've not seen any report of them being available after the closure.
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