Found the answer in the FAQ: https://learn.microsoft.com/en-us/powershell/scripting/install/microsoft-update-faq?view=powershell-7.3
I am on PowerShell 7.2, why have I not been upgraded to 7.3?
The Microsoft Update feature for PowerShell only updates versions in the same release channel. PowerShell 7.2 is the latest long term supported (LTS) version. PowerShell 7.3 is the latest stable (non-LTS) version. Microsoft Update automatically updates you to the next patch level versions for both 7.2 and 7.3. For example, 7.2.x to 7.2.y and 7.3.x to 7.3.y. For more information about support lifecycles, see PowerShell Support Lifecycle.