I've never heard before that it would be so dangerous to smoke while on hrt. I started smoking when I was 18, started taking hrt at age 21. I'm now 29, still smoking and just went off hrt for unrelated reasons. Meaning my reasons had nothing to do with my physical health. I'm just detransitioning. I'd say I'm a quite heavy smoker, and need cigarettes every day. I also smoke to keep my mental health in check, but also because I just really love to smoke.
I've never had any issues with it somehow interfering with my hormones, although of course I understand it's not a healthy habit in itself. If anything smoking was a bad combination with binding my chest (which I did for 5 years), cause that I'm pretty sure that reduced my lung capacity a lot (more than if I had either not been smoking or not binding) and messed with my breathing. I still get sporadic breathing issues and it's hard on my chest to just wear a regular bra now, even though it was over 4 years ago I stopped binding. So I'd say smoking while binding is probably much more harmful than smoking while on hrt, but of course, that might just be me and my cards in life.
I took testosterone for 6 years in total, and I smoked during all of those years, before and after. I only took a few months break for top surgery, but that's all. For the past 6 months or so my red blood cell count has been a little wonky which my endo thinks is due to the T and/or my diet but because I stopped taking it recently I'm pretty sure that will sort itself out just given more time off the hormone. It could have been caused by the smoking and T in combination, cause both smoking and sex hormones are known to mess with blood stuff. But that's all the issues I ever had with my hormones.
I'm not saying just because I'm fine then smoking+T is a totally fine combination, but this thread looks a little bit like fearmongering to me. Sure it has some increased risks and smoking in itself is factually dangerous, but it is possible to take hrt and stay a smoker and be reasonably healthy (meaning about as healthy as any smoker who's not on hrt), if you're willing to take that risk. It is an increased risk, yeah, but it's not that dangerous.
I'm not advocating for staying a smoker, or starting it, for that matter. I'm just saying it should be your choice and it's good the risks are being highlighted, but I kinda don't like this trying to scare you into quit smoking that's going on here, cause I just don't like that kind of tactic.