The invention relates to an assembly for an aircraft turbomachine, comprising a central element (1) for the ejection of gas, and a connecting flange (9) interposed between, upstream, a gas outlet (22a) made of metal for a turbomachine, and, at the downstream end, the central element (1). The connecting flange comprises an annular portion (9a) and flexible tabs (11) having axially: a first end (111a) where the tab is connected to the said annular portion, and a second free end (111b), projecting radially inwardly with respect to the first end and to which said tab is attached with the central element (1).