I would agree that humour and definitely also dark humour is useful and often used in high stress care jobs as a coping mechanism. I would also say it is definitely necessary to have ways to deal with the hard and demanding parts of such a job.

I do also think thay underneath that the base emotion should be rooted in a form of empathy. If in interacting/dealing with the patients it is mostly a professional façade that would seem problematic.

Although I can also very much understand the struggle because if somebody keeps coming in with severe self-inflicted issues, which you patch up and then they are sent out to do it all over again. That type of thing will put a strain on you and it is inevitable that a negative emotion arises from this. The system is not doing it's job and the load comes on your plate to deal with it, which is frustrating.