Increased Costs - Covid Z Clause

We have a Z clause under clause 60 which states:-
the Subcontractor’s ability to Provide the Subcontract Works is adversely affected by the Direct Effects of the Coronavirus.
The subcontractor does not have a X1 clause, but is claiming increased costs on materials stating that their ability to provide the works has been affected by price increases and if they had not purchased materials at enhanced rates production would have been affected.
I do not believe that increases are a direct effect of Covid, but are generally inflationary.

Thoughts?

to better understand can you please provide the definition of Direct Effects

There is no definition I’m afraid. It will need interpretation.