It must be the inoperative normal braking and autobrake. I looked in our OMs, as we have both generations with NWS on G or Y hydraulic.
Only in case of G SYS LO
PR *WHEEL is listed as a secondary failure. Not in the case of Y SYS LO
PR, no matter which system supplies the NWS. And while it is true that you will have to extend the gear by gravity extension and L/G RETRACT is inop (as both indicated on the STS page), there is no indication of that on the WHEEL SD page. Only NORM BRK, AUTO BRK and STEERING are displayed in amber (and because there is never a *WHEEL secondary failure with Y SYS LO
PR, it can't be the STEERING part). As you will have to analyse the associated SD in case of a secondary failure during the ECAM actions as per "Handling of ECAM" it can't be the gravity extension or inoperative retraction, because there is simply no indication of that on the wheel page.
Why only the braking part is classified as a secondary failure and not the steering I don't know...
