There are some good points regarding policy, like if there are anti smoking policies then suicide risk is lower.
I think there are two kinds: chill balanced smokers and smokers who think it is bad for them and use it to show slow suicide. So I am not surprised smoker suicide rates are higher. Anti smoking policies reducing suicide is interesting. could be preventing a mild suicide from starting helps it not graduate to more serious. Mental health decline after starting smoking != mental health decline from nicotine, I bet it is real and big part of it is nicotine but doing daily and visibly something much of society frowns upon probably "helps". And also just knowing that you are killing yourself, if you are that kind of smoker
Them saying that drugs can cause depression is basically saying nothing (basically same as "not using drugs can cause depression").
It's confusing that Serbia beats almost everyone by amount of smokers, it is the most smoke filled place I visited but it is not even in the top in https://www.wcrf.org/preventing-cancer/cancer-statistics/lun......