The memo states that the league will "closely scrutinize" trades where injured players are acquired with the intent of keeping them on LTIR until the playoffs. They said they aren't banning these types of trades but will be investigating them to see if they circumvent the CBA.
In the past, we've seen teams like Tampa and Chicago keep their own player (Nikita Kucherov, Patrick Kane) on LTIR and use that cap space to acquire a player or players at the deadline and then activate them for game 1 of the playoffs. Hence Kucherov's "18 Mil Over the Cap" t-shirts after the Bolts won their first of back-to-back cups.
The memo could impact the trade market and value of players like Gustav Nyquist, Sean Monahan and Adam Henrique, who are all currently on LTIR dealing with injuries, but who might be healthy at some point during the playoffs. Trading for these players and others on LTIR could come down to the idea that they will play at least 1 regular season game for the team that acquires them before the playoffs to avoid teams circumventing the salary cap.