Block outdated AVD clients

Hmmm, the only thing I can think of is to enrol those devices into Intune and then create a custom compliance policy which is in preview to check for the version of the AVD client installed onto their devices, other than that I can't think of any other way, be interested to know if you come up with anything though. To be fair, the AVD client by default does auto update itself on Windows devices so it shouldn't be too much of an issue I wouldn't of thought?

Here's the link to Intune custom compliance policies if you're interested: https://docs.microsoft.com/en-us/mem/intune/protect/compliance-use-custom-settings