I don't think career plans matter. Workload does. If you have a work plan and taking any free days puts it in jeopardy, you will not take any extra free days. And if not meeting the full work plan results in no salary updates, which is technically not a punishment and it is allowed by law in most of Europe, with some inflation (over 10% in my country) it is practically a pay cut, so you can't afford that.
That would certainly not fly in France, it would land the employer in a tribunal. Paying someone less because you gave them more work than could be completed during working hours?! Non, impossible.
