I have no idea what the topic was
The bear vs man story was a social commentary thing where women were trying to show men how dangerous and confusing men often seemed to be with an anecdote about whether or not they would want to run into a bear in the woods or a man in the woods.
Women tried to make clear that they would most often want to run into a bear, because they know what a bear will do. They don't have to constantly second-guess themselves about the nature of the bear. The bear can be scary, but if you're prepared and know what to do, you can make it out alive.
The opposite is how they feel with men. They feel like they cannot know a mans actual intentions in the woods and it could be anything from wanting to help her if she's lost all the way to leading her to a rape/kill dungeon in the woods.
Thus, they would rather run into the bear where they can always know the bears intentions, and thus always know how to properly respond to the sight of the bear, they don't ever need to second guess themselves on the intentions of the bear. Whereas they have to treat all men as though they are their worst iterations just to be safe, and that can be frustrating and confusing and they also know that it's hurtful to treat men who may not be terrible that way. Yet they feel the need to do so to feel safe and secure and not be taking a risk.
Now, as for a specific conversation on Lemmy that lead people to believe Lemmy was worse for women than reddit. I couldn't point you to that, but that also would not surprise me in the least. Lemmy overall does seem to skew heavily on the side of cisgender men. The blahaj lemmy is pretty small compared to others, for example, and probably hosts the largest number of genders other than cisgender men.
So honestly, I would not be shocked if there was a discussion around the "man vs bear" thing and that a lot of men on Lemmy had negative views on the whole thing instead of being able to see the other perspective. It seemed that men in general had a very negative view on the whole thing, probably because it made them feel personally attacked. Which was never the goal by women, but rather to just try to get men to hear them, really hear them on why they felt so sketched out about strange men approaching them in public.
I think a lot of it boils down to men having their own issues with women, especially men who try to be decent people. That can be seen in the response meme from men "Would you rather be emotionally vulnerable with a woman or with a tree?" The implication being that while men are often told to "open up" and "just talk about their feelings," a large number of men have had very negative experiences when actually doing so. The number of women who think a man who cries is weak and will dump him is, well, too damn high. So emotional availability and vulnerability are things men feel that women want, and women indeed often say they want... but when faced with them, women will often get an "ick" and dump a guy over it. So men would rather be emotionally vulnerable with a tree so they don't get judged for being emotionally vulnerable.
The real issue is that "man vs bear" or "woman vs tree" are entirely different issues which don't really cross paths nor address the same issues or ideas. It leads to both sides sort of talking past each other instead of listening and hearing what the other side is actually saying. I think both of these positions have value to their respective genders, but both sides could do with a healthy amount of actually hearing the other side in this regard, instead of being dismissive.
Also, personal opinion, it says a lot that men also cannot feel safe being emotionally vulnerable with each other. Why would they go to a tree first instead of another man? Because other men will treat them as weak, too.