Great news and being in the bakery section will suit you. Why the shortage of labour? I'm not sure there is that here for supermarket work.
It is simple in the US, people, most often in the lower paying jobs, but also in higher paying service jobs, are working harder than before covid to save their employers overhead, but not getting paid more money. So they are quitting to find better paying jobs.
Waitstaff in restaurants are the prime example. To save money during lean times, restaurants in much of the US are using fewer servers to wait on the same number of tables, and expecting the servers to bus their own tables, in many cases. But, they are not getting paid any additional wages. Plus, with tips (which is most of a server's income) down, they are burning out.
In some higher paid, professional jobs, the same thing is happening. My sister is a Registered Nurse in a hospital (that happens to have a lot of covid patients, too), and she is working much harder now, and her pay hasn't gone up commensurately. A Registered Nurse is a job that requires a college degree, and a license requiring yearly continuing education and testing, so it is not menial labor. My sister is constantly on the edge of burnout, and hasn't had a decent raise since the pandemic started.
On the other hand, there are some professions/career paths (and age groups) where people can't get a job in their profession/career path. They, including me, are going to eventually settle for a lower paying job in another field. It's a weird economy since covid came along.
CD