They tend to put those on the Yummy magazine. Some of these guys are willing to do frontal shots but not all of them. This one will please the buyers who like sexy shots of fashion, print and fitness models, even though some of the guys are not showing the dicks.
Yummyzine is the smaller sister magazine and they more often use Onlyfan models and porn stars, who obviously are willing to do frontal shots. This will satisfy those buyers who just want to see dicks and don't care much about the background.
It is not 100% rule but they seem to go by this split most of the time now. In the earlier days, they did put fashion models in Yummyzine as well.
I don't think it has to do with the magazines but with the photographers. Good models tend to shoot more with good photographers and in this case we are talking about Smiggi, Sasha, Steven Klein, Sgura, Oita, and a few others. For example, Sasha is working on Yummyzine 7 and Yummy 9, and I believe out of the 15 models he shot for zine 7, only Matt Dubbe has an OnlyFans. However, the other photographers shooting for the zine are mainly shooting models with OnlyFans. Agencies don't let their models shoot nudity with just anyone because, in the end, it's not about what you shoot but who you shoot it with and the opportunities come along with that.
Giorgio got to work with Armani and Dsquared2 because he shot with Sgura, Paul Ferrari did a recent collab with Fiat/ Armani because he shot with Sasha, Elia Cometti got to do Ron Dorff because he shot with Smiggi and agencies see that.
So, I wouldn't see it as linear as OF models go into Yummyzine and others into Yummy, but rather as which photographers tend to shoot more models that have agencies. Every agency in Milan and NYC knows that the Yummy big five are Sgura, Klein, Oita, Smiggi, and Sasha.
Then, there are a few good photographers that come and go, like Wong Sim and some others. The lower tier photographers shoot mainly with OnlyFans models because those models are more accessible to everyone, and you don't need to be a big photographer to work with them.