Why a year? Emergency measures being valid for the duration of the emergency would be pretty straightforward.
Deciding when the emergency is over is less straightforward than a fixed time period. A government that wanted to extend the measures indefinitely would just claim there's still an emergency.
And even if the emergency is not over in a year, it makes a lot of sense to reconsider if the measures (which were decided very quickly) are actually appropriate and necessary going forward. Hopefully a lot have been learned in a year.