Is it permissible, from an Islamic perspective, to receive profits from electronic games that were originally permissible but then had a gambling mode added to them, knowing that the chosen mode of play remains permissible and free of gambling?

If the game is permissible and offers rewards, then there is no harm in benefiting from it. The money you obtained is lawful, and you may play in the future and acquire money in the same manner. However, buying tickets or similar items is not permissible, because it is gambling.