On my Librem 15v2 (with AMI bios and Debian), I have the same problem. I once left the laptop suspended for ~48 hours, it fully drained the battery. Please note that I configured the USB ports to sleep when idle through powertop (and it works, since I have to toggle them back to “normal” if I want to plug in a usb mouse, otherwise the mouse goes to sleep after a very short time of inactivity).