Probably an escape from the botanic gardens. The local shrubby Solanum, growing naturally at higher altitudes in the ACT, is linearifolium, which occasionally has lobed leaves.
Solanum linearifolium grows around Canberra, not just high altitude, but I am not sure about lobed leaves. There are photos of Solanum aviculare with toothed leaves but these don't seem to be mentioned in descriptions.
From PlantNET: Solanum aviculare G.Forst. Leaves lobed or margins entire, concolorous, glabrous; lobed leaves broad-elliptic to obovate, 15–30 cm long, lobes 1–10 cm long, 0.5–2 cm wide, petiole to 4 cm long; entire leaves lanceolate to narrow-elliptic, 8–25 cm long, 1–3.5 cm wide, petiole 1–2 cm long. Couplet 15 in the PlantNET key using leaf length and width separates Solanum aviculare from Solanum linearifolium and Solanum vescum. Otherwise they seem to be separated on fruit colour.