cat /sys/power/mem_sleep
will return "s2idle" and "deep" values, value surrounded by square brackets will show which mode is currently activated.
Probably when you observer battery drain during suspend, you will see "s2idle" highlighted.
To change it do deep sleep mode use command:
echo deep > /sys/power/mem_sleep
To make change permanent add the following to your kernel cmdline in your bootloader, edit /etc/default/grub file and put mem_sleep_default=deep parameter at the end of line containing GRUB_CMDLINE_LINUX string.
mem_sleep_default=deep
Next thing is to rebuild GRUB2 config file.
For BIOS computers:
sudo grub2-mkconfig -o /boot/grub2/grub.cfg
For UEFI computers:
sudo grub2-mkconfig -o /boot/efi/EFI/fedora/grub.cfg
After reboot again verify using:
cat /sys/power/mem_sleep