to have something to do with

AS CED says, be/have something to do with something is ill-defined:

be/have something to do with something informal ​

C1 to be related to something or a cause of something but not in a way that you know about or understand exactly:

I'm not sure what he does exactly - it's something to do with finance.

(ie is related to finance. Here, 'finance has something to do with what he does' doesn't sound idiomatic. Probably because 'finance' is the wider field, 'what he does' a small part or small overlapping area. But with 'equivalents', like 'locks have something to do with keys', the A and B are reversible.)

..........

It [the fact that it is brittle] might have something to do with the way it's made.

(ie It might be something that results from how it's made.)

In this case, 'The way it's made might have something to do with it being so brittle' (the reverse causative; CED does not give the 'or be caused by something' sense) seems to work.