This answer is from an Austrian perspective, but I guess the regulations are quite similar to Germany. The so called 'Abfertigung, Überstunden, Urlaubsanspruch/- geld, Weihnachtsgeld' which remained unused/unpaid on your last day after serving your notice period should be payed in full with your last paycheck and be listed on your last payroll ('Lohnzettel').
The last wage (which has to include the above mentioned positions) is to be paid with the same due date as a normal wage in the employment relationship. This means that if there is no other regulation in the employment contract, then the statutory regulation, according to which the wage is due on the first day of the following month.
Employment contracts or collective agreements often contain expiration provisions, according to which outstanding claims must be asserted against the employer within a few weeks or months or even sued for.
Unless a written assertion is required anyway, it is advisable to always assert open claims in writing - if possible by means of a registered letter. In the event of a dispute, proof can also be provided.
However, all open claims must be asserted in court within 3 years, otherwise they become statute-barred!
I would contact the salary-department ('Lohnverrechung') of your former employer (keep in mind that some companies have their salary department outsourced) for immediate clarification as to why those are not listed and payed.
Make sure you contact them in writing (e-mail or a registered letter) and keep the paper-trail. It might be just a mistake on their side , but in case they refuse for whatever reason they might come up with or try to ghost you, your next step should be a visit to the closest local office of the 'Kammer für Arbeiter und Angestellte'. They offer free legal advice and are knowledgable about what steps to take next in order to get things straighten out. If they still don't comply with your justified request to get paid, there's always the labor court ('Arbeitsgericht').
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