The support article mentions an option that you can toggle, but it seems to be exclusive to the Workstation Pro version.

It turns out the message about side channel mitigation appears when Hyper-V is enabled in the host, Windows. I'm not really sure if it has something to do with the Trial version of the Pro variant that I had been using, so I ignored it and tried using the VM, but it was really slow and simple actions like opening files took a long time to complete. It said that there maybe some performance degradation with side channel mitigations enabled. On a side note, VMware Player recently started displaying a warning on my computer. How to disable side channel mitigations in VMware Player

If you want further confirmation that TPM is working correctly, install and run the PC Health Check app in your VM, and it should no longer say that your computer doesn't support TPM 2.0.

Access the virtual machine's settings, and it will list TPM as an option, though you can't edit it with the free version of the application.

If you shut down the operating system, and run VMware Workstation Player again, you will see a padlock icon next to the OS indicating that it encrypted. You may use Window Insider Preview ISOs too. Start the application, and install Windows 11 normally.

Windows 11 vmware workstation pro