Revice Password Last Set logic to check local PasswordLastSet and msLAPS-PasswordExpirationTime
Is your Windows LAPS policy targeting the built-in admin account, or a different account that you are creating?
Can you provide more details about the nature of your "template" images? Are they sysprep'd? Were they previously joined to Active Directory, AND did they have Windows LAPS policies applied?
I am intrigued by your issue, please do lmk. You're correct that Windows LAPS does not currently check the PasswordLastSet state of the target account - but we do maintain other local state (primarily under HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\LAPS\Config) that if missing or inconsistent will also trigger a fresh password rotation regardless of msLAPS-PasswordExpirationTime. So I am really curious what values are stored under the LAPS\Config key in your template images.
thx,
Jay