Users are being prompted to restart their non-persistent desktops in the middle of the day.

non-persistent VDI machines are deleted when they are rebooted, logged off, or shut down. Therefore, Windows Update policy should be configured to prevent automatic updates that may trigger a restart on these machines1.

https://techcommunity.microsoft.com/t5/microsoft-defender-for-endpoint/onboarding-and-servicing-non-persistent-vdi-machines-with/ba-p/1360721