The 28-year-old joined the Italian club last August for £38 million — £15 million less than Chelsea paid RB Leipzig for him in 2023.
His two-year spell at Stamford Bridge yielded just 18 goals in 62 appearances, a period heavily disrupted by injury, before Milan emerged as an escape route.
The move to the San Siro has not resolved matters. Nkunku has managed six goals in 31 appearances across all competitions, with five coming in Serie A and one in the Coppa Italia.
According to Tutto Mercato Web, Milan have placed him on the transfer list ahead of the summer window. The primary reason is a mismatch in profile — Allegri prefers a more physical centre-forward, a preference that has seen German striker Niclas Füllkrug, signed on loan from West Ham United in January, jump ahead of Nkunku in the pecking order alongside Christian Pulisic and Rafa Leão.
Nkunku is expected to attract interest despite his underwhelming recent record. Turkish club Fenerbahçe made an approach in January, and clubs from the Saudi Pro League are also monitoring the situation ahead of the summer window.
A sale would allow Milan to recoup a portion of their outlay and free budget for Allegri to pursue a more suitable profile up front.