In his 2012 CDM proceedings, Peter Scholze mentions the following open question:
Let $K$ be a perfectoid field and $(A,A^+)$ a complete affinoid $K$-algebra. Suppose there exists a cover of $X = \text{Spa}(A,A^+)$ by rational subsets $U_i \subset X$ such that $\mathcal{O}_X(U_i)$ is a perfectoid $K$-algebra. Does it follow that $A$ is a perfectoid $K$-algebra?
Has there been any progress on this question since then?