Let me try to explain with an example. GAAP requires straight line depreciation of a lease. So if I gave you a 2 year lease on a facility and required a single payment of $1M at the end of the term, you'd account for that as 500K expense in year one, 500K in year 2. In year 1, your cash balance didn't change though right? I only wanted payment in year 2. So you record a 500K deferred rent liability to indicate that the expense has yet to hit your cash balance.

Basically over some set of future years they'll have to pay out 2.8B of cash. But they don't disclose the timing on when those payments come due.