In the Czech Republic you do not get bonuses to your scholarship (stipend). It is forfor everyone and increases with you getting some exams or getting to the second year.
However, if the PhD student is actually employed (in a regular type of contract, not a one-off task), they can receive any bonus that other employees get. It is quite common. I would not expect some of the employees to be skipped just because they happen to be students.
This is a a real bonus -– it is only possibleavailable if the department has the money. It does not come automatically and there is no entitlement to it.