I’m with @livelaughlove21. You have nothing to gain by reporting it, and you have nothing to lose by not reporting it. It’s clear because of the date stamps that you are the first person to have posted the answer. So, the options are (1) the prof didn’t notice, or (2) the prof noticed and is choosing not to act, or (3) the prof noticed and is choosing to act, just not that you’re aware of.
My own experience being a teaching assistant for several years is that my attitude towards cheating shifts over time. I detest the thought that my students might cheat, partly because it’s a waste of my time, but mostly because it’s an insult to the students who are working hard to get a good grade. But catching cheaters is a huge problem. Depending on the institution, there may be very little support for a teacher who reports cheating. Some institutions are more afraid of lawsuits from students than they are of having their academic reputations sullied.
So, my approach is to make it very difficult for students to cheat. This makes the grade meaningful, and it reduces (not eliminates) the risk that I’ll catch someone cheating. But that’s just me. I have known other TAs and profs as well who simply ignore cheating, because they know the student will not be punished, and it’s a waste of time and emotion trying to get it dealt with. For a lot of these people, their attitude is, “The only person the student is cheating is themselves.” This is a valid point – in higher education, each student is there to acquire knowledge and skill. And whether or not they get a degree, if they don’t have the knowledge, they are the ones who are cheated. The other attitude I encounter is, “The cheating student can’t cheat their way to a pass, because there are different types of assignments in the course. So what if they cheat on an assignment – they can’t pass a final.” Sometimes this is true, sometimes not. On average, it’s probably true. I haven’t adopted either of these attitudes yet, but I grow increasingly aware that I don’t have the kind of time that I need to put into these teaching jobs that is required to catch cheaters. I need to invest my time in prevention, and then spend less time watching for it to occur. So, I think it is inevitable that my thoughts on the matter will eventually change.
My point is that a lot goes on that students are not aware of. There is a lot of cheating. More than you can guess. We get tired of it, and we get tired of not being able to make a difference in it. You’ve made some accusations here about your teacher – she doesn’t seem to care about the course or her students. If that’s really true, I don’t see what reporting these students is going to gain anyone. If it’s not true, then you’ve created an antagonistic situation with your prof over nothing. A complaint to the dean will probably result in nothing. It is the prof’s responsibility to deal with the problem, and the chain of command will have to be followed. Report it, or don’t report it – but it is futile to spend your energy worrying about what will happen to these students, or about your prof’s lack of attentiveness or outrage.