Players sued the league over what is referred to as «Concussion Litigation», seeking justice for the lack of protection that led to concussions and later problems in life for the players. Nevertheless, the NHL settled the lawsuit and spent $100M in doing so.
And that $100M is the crux of the issue Rick Westhead is explaining. The NHL is insured for legal expenses, but their insurers have only reimbursed the league $20M.
The NHL has now requested a judge to further inspect the concussion litigation the NFL and NCAAs faced, as the same insurance companies backed those leagues through similar litigation.
The legal battle for the NHL to be reimbursed it's missing $80M will continue, likely for years. You can read Westhead's article below, through a link in his Twitter thread - he's truly the most important follow in hockey journalism at the moment.