How to prevent my laptop from (re)starting after shutting down?

My laptop keeps (re)starting after I choose 'shut down' in the start menu. I find this very irritating, as I like my laptop to be shut down when I'm not using it for a few days. Similarly, it tends to start up already if I put it in a bag and start walking, without opening the lid or touching any buttons.

Infrequently the laptop even rebooted while I was actively using it, or after a couple of minutes of inactivity (which should trigger sleep mode according to the power settings, not reboot)

Things I tried to exclude:

• It is a new laptop (around 1 month), I gave it time to do all updates (actively opened this menu most times I use the laptop), used it over 10 times
• I disabled 'automatic restart' via sysdm.cpl 
• I tried different power settings all without success

Laptop model: Lenovo IdeaPad Slim 5 OLED 15ARP10 83J3002VMH

15.1" 2560x1600 (WQXGA) OLED 165Hz, AMD Ryzen 7 7735HS, 32GB, 1TB SSD, AMD Radeon 680M, W11 Home