The Division 2 beta apparently needs a restart every two to three hours
https://www.pcgamer.com/the-division-2-beta-apparently-needs-a-restart-every-two-to-three-hours/
The Division 2 private beta is now underway and Ubisoft has advised players to restart the game client "every two to three" hours to avoid crashes.
In an announcement on the official site yesterday, Ubisoft advised players that it's aware of some "high priority issues" present in the current beta. While the devs are keen to get them fixed, the workarounds offered should give players a better experience.