NG decks regardless of leader ability(Mostly Enslave, DC, Imprisonment) started running Guillaume+milton in their decks without any real synergy as a really good midrange package. There is no real reason to play these cards with TH leader since the control the other decks offer is much better. Even against TH decks the particular combo is enough to counter it while having the flexibility of playing locks/tallpunish while also following their own gameplan.
Couple of patches ago we had similar problem with all ST decks running zoltan and munro combo. I'm glad that was reworked to support the archetype they were intended for and not auto include in every deck.
Hoping for a similar rework for these cards so that they're not auto include outside their intended archetype. I'm not gonna give any suggestions regarding what the reworks could-be or should-be as i'd rather not turn this post where people start arguing balance and provisions. Making this post to bring this problem into the light sooner rather than later though i see some streamers talk about this issue already. So hopefully we might get some reworks in the upcoming patch.
Source: https://www.reddit.com/r/gwent/comments/ycbklg/we_need_reworks_for_ng_boost_guillaumemilton/