From the article, Table 3: 100% SoC @ 25°C leaves only 80% of the original capacity after a year.

It's easy to look at that table and think that it's remaining charge after a year; it's not. It's lost capacity.

This is known in the industry as "calendar aging". So far as I know, stockpiles of lithium ion batteries are stored at a relatively low state of charge and in a cold environment for this reason among others. It's common to order a laptop battery or similar and get a unit that was manufactured a year back. It would be terrible to get a new battery that already had diminished capacity, which is what would happen if you stored them in a non-conditioned warehouse in a hot climate.