• When placing an Esxi host in maintenance mode DRS may fail to automatically migrate VM's that have vGPU enabled.

• Under a Cluster's Monitor tab the "vSphere DRS" -> "Recommendations" section may have a VM Migration recommendation for vGPU VMs with a Reason "Destination host is selected for fixing policy/rule violation or its healthy state is better".

• Manually vMotioning vGPU enabled VM's is working as expected.

This is expected behaviour at this time. Per the documentation, DRS will only complete initial placement of a VM with vGPU, but will not automatically load balance:

Using vMotion to Migrate vGPU Virtual Machines (vmware.com)

"DRS supports initial placement of vGPU VMs running vSphere 6.7 Update 1 and later without load balancing support"

Starting with vSphere 8.0 U2, DRS can estimate the Stun Time for a given vGPU VM configuration. When the DRS Cluster Advanced Options are set and the Estimated VM Devices Stun Time for a VM is lower than the VM Devices vMotion Stun Time limit, DRS will automate VM migrations.
 
To enable this functionality, make sure the infrastructure meets the following requirements:

• Healthy vSphere Lifecycle Services (see https://kb.vmware.com/s/article/91891)
• Configuration of the VM's vGPU devices through the VCenter UI only
• Healthy vMotion network (e.g. vMotion NICs setup through https://core.vmware.com/resource/cluster-quickstart)

Then add the following DRS Cluster Advanced Options:

Option: PassthroughDrsAutomation
Value: 1
 
Option: LBMaxVmotionPerHost
Value: 1

For vGPU VMs with Stun Times exceeding the "vMotion Stun Time Limit" (default 100 seconds), a VI Admin can add the following DRS Cluster Advanced Option:

Option: VmDevicesStunTimeTolerated
Value: <number of seconds, greater than any VM's Estimated Stun Time in the Cluster> (Default 100 seconds)

OR

Modify the "vMotion Stun Time Limit" in the VM's Configuration -> "VM Options" Tab -> "Advanced" Section

For older releases, to resolve the issue please follow the below mentioned points:

• For Maintenance Mode evacuations, please refer vGPU Virtual Machine automated migration for Host Maintenance Mode in a DRS Cluster.
• If VM placement issues arise, reduce "DRS Automation" to "Partially Automated" please refer Creating a DRS Cluster for more information.