What i have seen, several times in my career, after being out for 6 to 9 months, was mostly a degradation in SOP skills, but surprisingly not in manual flying ability, that was like riding a bike. Getting my time management and smooth flow of SOPs back to normal was more of an effort.
Now, airlines are very much aware about skill loss, and in my experience usually plan extensive training before one is allowed to fly unsupervised again. And yes, even short haul guys have been sitting on the ground for 2 years now. In my current outfit the return to work schedule for those who have been out so long is pretty much a full OCC, so one or two weeks of ground school and quite a few simulator sessions followed by mandatory line flying under supervision.