Is working in the manufacture of discs that may contain unlawful content, albeit in a small proportion, permissible or forbidden, and what is the ruling on what has passed, and is it obligatory to leave it immediately or upon finding an alternative, and does giving away a proportion of the unlawful earnings from the salary as charity make it permissible?

If the factory is engaged only in the manufacture of molds and has no connection with forbidden cylinders, then there is no harm in you working there. However, you should advise them not to sell these molds to anyone who would use them for unlawful purposes. But if the factory produces forbidden cylinders, then it is not permissible for you to assist them, unless your work is restricted solely to the permissible cylinders. Otherwise, you must seek another job, for Allah Almighty says: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression." If leaving the job would lead to your ruin and the ruin of those you support, then it is permissible to remain temporarily while searching for a job free from unlawful things.