What are the big problems for commercial real estate? Higher interest rates if you're trying to refinance, of course. That seems to be the most obvious. Next up, skyrocketing operating expenses. Insurance, utilities, payroll and benefits, and repairs and maintenance have seen drastic growth.

What gets less attention but could take a larger bite out of NOI? Concessions, as Moody's notes specifically about office properties. It's almost invisible. There are no tax authorities, Federal Reserve, vendors or employees, or anyone or anything else requiring a certain revenue share. Instead, the mechanism is negotiation with a great deal of opacity. Two parties push their interests and weigh the options of a deal or saying no and walking away.

The basic conditions are set by figures like what percentages of employees work from home and how much space each will need. As a separate Moody's report said, there will likely be an ultimate decline in vacancy rates to between 12% and 14%.