Dear @Anastasiia,
Welcome to the Wefugees Community and thank you for your question.
On the official website of the Bonn municipality I found a table which indicates 910 EUR gross rent without heating as appropriate for 4 people receving jobcenter allowance in Bonn. However, the exact calculation may differ - depending on your individual situation (i.e. for people with disabilities). Therefore, the 910 EUR rent with maintenance fees without heating and warm water is just an approximate orientation.
I hope this helps and please don't hesitate to get back to us with any further questions.
All the best,
Meike