Accessory power still on with engine off

[dev]

Hi,
My 2016 Z (~30k miles) has been having an intermittent issue with the ACC power remaining on after the engine is shut. It started over a year ago and has recurred sporadically, but is now more frequent. When it happens, the radio and the center console display will stay on (says “Climate Control”) and will drain the battery - unless I remember to switch the radio off and to manually turn the display off in Settings. Most times the yellow “Key” light left of the steering column also illuminates, though just for a few seconds. The power mirrors also work when the radio is stuck on and ignition switched off. 1 yr old car battery tests good. Key fob battery fresh/replaced.

I”m thinking the ignition push switch may not be shutting accessory power.
Or maybe the ACC relay is getting stuck (IPDM, and a bigger cost).

Plan to ask dealer and thinking there may be coverage under CPO Service+Plus.
But thought to ask for any ideas here first…