Noticed a Bug in FGU today: (Latest Update 20-06-25)
If you have only 1 Class and a XP Penalty it calculates the required XP for levelups correctly. If you have more than 1 Class that is active (For example a High Elf Fighter/Mage) It calculates the required XP for one Class correctly and for the other it seems like the added value ist divided by 100