Hi @Simar sahi
The maximum length of time someone can be deported back to another EU country is 18 months. After that, Germany has to assume responsibility for the case. Here is the information in English directly from BAMF:
https://***.bamf.de/EN/Themen/AsylFluechtlingsschutz/AblaufAsylverfahrens/DublinVerfahren/dublinverfahren-node.html;jsessionid=880A77A31C25E601FC808BD400414F2F.intranet662
Best,
Éanna