The periodic de Rham conjecture for completely reducible objects

Let $U$ be a smooth curve over $\mathbb C$. Let $\mathrm{PDR}^{ss}(U)$ be the full subcategory of $\mathrm{PDR}(U)$ consisting of completely reducible periodic de Rham bundles, and let $\mathrm{MDR}(U)$ be the full subcategory of motivic de Rham bundles.

Periodic de Rham conjecture.

$$\mathrm{MDR}(U)=\mathrm{PDR}^{ss}(U).$$

The source obtains this conjecture by combining the extension conjecture with the weak periodic de Rham conjecture. It strengthens the individual-bundle formulation by asserting equality of the motivic and completely reducible periodic categories.