COVID-19 continues to affect the NFL's salary cap which isn't expected to get back on track with increases until 2023. The 2020 season saw almost no fans in stadiums which affected team revenues. Fans returned to the stands this year, but teams are still hedging, and holding off on a full return for player salary cap money for a little longer.
The NFL sets their salary cap every year in March, and it was steadily rising by $10-12 million since 2013. A new CBA was signed in 2012 after a lockout, and TV deals pumped a ton of money into the league’s coffers which allowed the pot to grow for players.