If it is, it certainly isn't in regular use. The area it leads to is exclusively for pedestrian use and is blocked by a fixed concrete flowerbed, which can be seen on this page https://www.buildingsofireland.ie/buildings-search/building/20503284/wandesford-quay-cork-city-cork-city-cork

The concrete tracks inlayed with the paving stones of the tunnel may mean that vehicles used it at some point, but the curb is not lowered, nor damaged, and there is no sign saying the gate is in constant use (like almost every other vehicular access point in the city) I wouldn't say this should be mapped as it was previously with a highway tag