From how I see it T4 is already a full lockdown and iirc over half the country is in T4 already so I don't see how things can be much different in January.
Then there's things like only being allowed out of your house once a day for exercise.
And maybe if your work can't be done from home you're paid to stay home and not do it unless it's an essential service?
Key things are
1. This is only for a short and bounded time while we roll out vaccine 2. We need to get numbers down so that vaccine rollout isn't impinged