Doing the DDQ, as you do, and I went with my go-to 1* team of Juggernaut, Black Widow and Storm…because I use Ares, OBW and Storm in 2* land and it’s quicker this way.
And yet in the first node is OBW and I wasn’t restricted from using BW.
To double check, I did the 3* Required Character node that had 2* Bullseye, 2* Thor and Bagman. I was able to choose 3* Thor, 3* Spider Man, 3* Bullseye…hell I was even able to choose 2* Thor and 2* Bullseye.
Now, I’m sure I’m not just being thick here. This wasn’t always a thing, right? In fact, in that node the only character that was restricted for me was 4* Captain Falcon…because he was required, natch. But no other character was restricted.