Nkunku, 28, joined the Italian giants from Chelsea in the summer of 2025 but struggled to adapt to life in the Serie A and beyond.
The Frenchman scored just eight goals and provided three assists in his 35 games across all competitions and has now returned to RB Leipzig.
In comments via Calciomercato.com, Nkunku said he ‘didn’t understand’ AC Milan’s decision to let him go while also conceding the club’s ‘philosophy’ didn’t suit him.
“When I went to Chelsea, things started well and then I suffered an injury at the end of the last friendly. After that, everything changed,” he said.
“I had my first operation, I wanted to get back on the pitch quickly and there were also many changes. I didn’t like my role at Chelsea.
“At Milan, on the other hand, I didn’t have any injuries, but the football philosophy was different from mine. So, as soon as I had the opportunity to come back here and play my football, I took it.”
Nkunku was then asked about Milan’s decision to let him leave.
“It’s a decision that has to be respected, but I didn’t understand why they acted that way either. I was surprised. In any case, I wish them a good season," he added.
The forward is nevertheless happy to have returned to Leipzig.
“I’m very happy to be here and I’m convinced I made the right decision. The first week has been fantastic and the team made me feel very welcome.”