A while back I posted about how my E-Pace's battery went completely flat when I left it for less than four weeks. Have since had to leave it for 8 weeks so took the precaution of using a solar powered battery maintainer. It worked. Battery fine on return.
The breakdown guy who came to rescue me when my car wouldn't start said it was becoming increasingly common. He reckoned that cars used to power down the alarm system to preserve the battery but now they aren't allowed to. Also now the lights have to come on when the battery is getting low. Brilliant idea. If it's to give you visible warning of low battery I didn't see it as I was 10,000 miles away at the time.
Based on my experience I would recommend anyone who is not going to use their car for 2+ weeks to use either a trickle charger or solar panel to maintain the battery charge.