Aufhebungsvereinbarung vs Termination?

Hello,

I need legal advice regarding signing an “Aufhebungsvereinbarung”. Some background:

• The company I am working for as a working student -half time, for more than a year now- had offered me to do my masters thesis with them.
• ⁠I agreed but then after a couple of months we couldn’t reach an agreement on the topic, while I was still under a working student contract, and had not signed a thesis contract yet.
• ⁠When I announced to them that I have decided against doing my thesis there, the manager said that they do not want to continue working with me and sent me a “Aufhebungsvereinbarung” for the end of the current month. (So almost two/three weeks) which they are pressuring me to sign immediately.
• ⁠I have moved to a different city and work remotely and this is one of the reasons they mentioned, as remote work isn’t favorable to them. But I have been traveling back and forth every month upon our agreement to be there in-person
• ⁠Obviously, they are annoyed that I have not followed through with the thesis commitment, but I am trying to keep things as amicable as they could be at this point
• ⁠I am on a student visa (international student) so I don’t think I would lose rights to unemployment payments signing this agreement, as I am not entitled to it anyways. Do I have to sign this? What happens if I don’t?
• ⁠they are saying I could just resign if I don’t want to sign this, should I do this instead?