I didn’t even know this was a thing. In fact, the NHL probably made it up while the COVID-19 pandemic did a number and a half on the league’s revenue for the year. The NHL is implementing Escrow Debt into their CBA in order to keep the Salary Cap flat for at least the next three years.
The NHL owners and players each earn 50% of the Hockey Related Revenue (HRR) made every season. This year, HRR is down massively and if the players earned only half of this, the cap would be in the toilet and back to their 2005-06 days.