The news report says "players who die within the simulation, or forcibly disconnect without using an authorized exit portal".
It doesn't mention anyone dying from using an official exit portal, or that there are damaged portals. It also doesn't mention the existence of "unauthorized" exit portals, though I can see how that might be inferred. To me, "authorized exit portal" sounds like typical legal phrasing that does not imply there are unauthorized exit portals. Who would have created these unauthorized exit portals? For what purpose? It's clearly intended to be saying "exit portals are the official way to leave the simulation, any method other than a portal puts you at risk" in order to minimise liability.
Are there enough players in combat or other risky situations such that 600k could die overnight? According to the Eternum wiki, up to 50 million people may be playing at any one time (out of over 420 million total—Orion is player 421,200,234). 600k is 1.2% of 50 million. This doesn't account for people logging on and off, so depending on how long it took for the danger to become known, more than 50 million may have logged on. It's easily believable that many players could die in a single day, based on the servers we have seen, especially if the Xenomorphs are spreading. It's also possible Ulysses themselves, or the Syndicate, caused an event that escalated the number of in world deaths beyond what is usual.
Forcibly disconnecting someone from the outside has always been dangerous, though usually not fatal, so I don't know that many people would be doing that. Idriel mentions when Orion first connects that logging off without using an exit portal is possible, but is treated the same as dying in Eternum. Exactly how one would log off without a portal isn't clear. It does not sound like the same thing as external disconnection, since this is known to be unsafe, and that seems like something she would have mentioned.
Now, Ulysses could be lying. Maybe people are dying who leave through the portals. But we don't know that from the available information.