I am coming back with a little clarification since i was pointed by someone on Twitter, and on the same subject, that i'm just partially correct. So developing a little. Hanbin has been credited by YG with being a lyricist and a composer for 4 out of 5 songs in the last iKon album. He's registered at KOMCA for all 4 songs and all is good on this side. However, people are arguing that he is also a producer and he was not credited by YG for that.
Let me explain to you shortly what being a producer means and why YG could not credit him as a producer. Moreover, YG has left the "Producer" section emtpy and totally removed it without listing other names, which in my book is more than respectful for Hanbin. But let's go to the definition.

Essentially, the music producer oversees all aspects of the creation of a song or album. These can include choice of song, choice of musicians, instruments and vocalist(s) and how those instruments are played and those notes sung as well as where the song or album is recorded. Like a
director is to a film, the music producer is to a song. Like a film director, the music producer has to be able to make split-second decisions and convey their vision of the final song to all those involved—the audio engineer, the musicians, the singer—in a manner that gets the best performance possible from each of them. The music producer needs to be able to focus on what’s going on in real-time as each track is laid down, as well as plan in advance by booking necessary
studio time and session players or backup singers for the additional recording sessions as needed. This requires great communication skills as well as an excellent understanding of logistics and budgets.

“The music producer is in charge of either writing the material or if
he didn’t write it, he’s in charge of organizing it and making it sound
like a cohesive song. He calls all the shots on what’s played, and when
it’s played, and how it’s played, and the sounds that are used, or the
vocals that are recorded if they’re correct or not. The producer is in
charge of everything.”

– Rick Camp, RC1 Productions & Master Mix Live – Las Vegas, NV

Credits: Jennifer Lopez, Beyoncé, Mary J. Blige, Kelly Clarkson, Usher, Dr. Dre, Earth Wind & Fire

So, in order for Hanbin to be credited as a producer of the album, he needed to be inside YG, working with YG and for YG, thing which we all clearly know is not the case anymore. YG had to re-arrange the songs, redistribute the lines made for 7 members to 6, do re-recording, pre-production, post-production etc, of which someone else has been in charge. Therefore, i call YG really nice for leaving the "Producer" section out of the covers and not putting other names in there as a sign of respect for Hanbin which did most initial producing part, but did not do the final product being out of the company.
I wish people would understand more of this industry before spreading false rumors etc.
Thank you for the patience in reading my thoughts.