Yikes.

Out of curiosity, is that a significant amount of air loss? Do they make it up somehow? I know they have oxygen generators on board, but I also know high-oxygen air is undesirable.

Oh shit. I hope everyone makes it out okay…

It went from 1 pound air loss per day to 2 pounds per day.

So it is significant in the statistics sense. That is a very measurable and sudden change which definitively shows that either a new leak has occured, or an existing leak has suddenly worsened.

However, 2 pounds per day loss is not severe on its own. Presumably the worry is that without knowing what caused the sudden increase, they can't know whether a sudden and much worse intensification of losses will occur. So the astronauts not involved in repair activities should be ready to evacuate until the situation is fully evaluated and a repair plan is ready.

Oxygen generators recycle CO2 back into O2. They can't create new air. So lost air is replaced from compressed gas storage tanks that get replenished from supply flights. 2 pounds per day is easy to supply from the tanks. The issue here is not knowing why there is a sudden doubling of losses and therefore lacking confidence that the situation won't worsen rapidly.