Intermittent login issues on macOS 15.1.1

Hi,

We're starting to see a number of cases being raised internally about some of our Macs (all on macOS 15.1.1) having intermittent login issues.  Our devices are bound to AD and our users have been logging on fine for some time but now we're starting to get issues.  Sometimes the logins are fine.  Sometimes they take ~10 mins and sometimes they appear to stall completely (waited over 2.5 hours in testing) even on the same device.  The login screen appears to freeze (the time doesn't change) and you eventually get the spinning beachball.  SSH is still working and you can run a "jamf policy" successfully.  "Screen Sharing" reports that the user who has attempted to log into the device is the active user when you connect.

Can anyone share some tips as to how we would start to investigate this sort of issue let alone resolve it???

Thanks

Stuart