The Phasmophobia servers went down earlier this week without players really understanding what had happened. Here's how you can tell this is happening in the future if it presents the same way.
Phasmophobia Servers Down: How to Tell
During the last server outage, players received an error message saying they couldn't log into their accounts. This is the main indication that the servers have gone down.
Although the earlier issue has been fixed it is still possible that servers might go down in the future. For one, the game is still in early access, meaning Kinetic might still be doing some work ironing out instability as evidenced by some issues in voice chat some players are experiencing. Additionally, the game is currently blowing up on Twitch, which suggests a lot of traffic is suddenly coming its way as possibly thousands of new players decide to try it. However, the previous server issues were already fixed so hopefully, this indicates that Kinetic is gearing up for and adjusting to the traffic headed their way. Since the game is still in early access Kinetic should have the time and data to adjust the game as needed for the official release.