It may well be that the key is not shutting down or is still within range and has been disturbed before you hear the noises, I’ve left my key indoors reasonably close to the car in the past and have noticed the the cars lights come on as I walked past the key that happened to be sat inside on a table near the front door, that table sometimes wobbles due to dodgy floorboards, in my case this probably activated the key and prompted the headlights to come on as I walked past the table, the key is usually kept further away from the car though, if you cannot keep the key elsewhere perhaps consider placing the key in a faraday pouch or box, my spare is always kept in a faraday pouch as it doesn’t get used, it may not be necessary as it kept quite a distance from the car, but in my mind it means that key is ‘shut down’ and as I already had the pouches from my previous keyless mk7 I use it anyway, I did initially keep the main key in a pouch to but stopped doing so when I realised these latest keys turn off if not moved for a few minutes, as mentioned, I generally keep this key away from the car and have had zero car battery issues, anybody that is having car or fob battery problems/drain should probably look at where they keep the key, and how often it may be disturbed in that location while not ‘in use’, the red light on the key will rapidly flash if it is currently communicating with the car, even if within range this flashing will stop after a couple of minutes if the key is not disturbed thus stopping communication, but if disturbed before you went to the car it would wake the car up, hence the noises, pay attention to the light on the key before you go outside and in what instances it’s flashing, you’ll soon work out what’s going on, but as I said, a faraday pouch will stop communication even if the key is disturbed thus saving the cars battery if this is happening very regularly.
This is the pouch I use, there are many other types available but I can only vouch that these block the signal.
https://www.ebay.co.uk/itm/28438586...p2LCNeJSEm&var=&widget_ver=artemis&media=COPY