TB16 Dell Thunderbolt or WD15 Type-C dock may experience the external monitor(s) randomly blank out. This can occur when you are on the newest BIOS and have installed all of the latest drivers. The problem is not limited to a specific video output connection or host system. The problem may also be intermittent and change after a reboot.
Cause information is not available.
Dell Engineering have created a new MST hub Firmware update for the TB16 and WD15 docks to resolve this problem. Please download the FW from the Dell Support website to resolve the issue:
The TB16 Firmware is here: https://www.dell.com/support/home/drivers/driversdetails?driverid=h3yg7
The WD15 Firmware is here: https://www.dell.com/support/home/drivers/driversdetails?driverId=PM4JN
Here are some recommended articles related to this topic that might be of interest to you.