@Zxcvbnm , I'm not sure if what I experience is exactly the same as you or not, but I definitely get a lot of thoughts about suicide and dying even when I am not "upset" - and even when I'm just going around doing my daily life things too.
Your feelings and concerns around it are valid. Are these thoughts and the reasons behind them something you'd like to explore more?
I'm curious -- but you do not have to answer any question I ask ever if you don't want to! -- whether this has been chronic thinking for you? Or something recent/new?
I also wonder whether the thoughts are more of a "curiosity" about it, or whether its more of a feeling of desire (even if absent from heightened emotion; a dissociation from emotion is also very possible, or even "boredom"/monotony)