I think it could be for multiple reasons
I see a particularly moving animal rescue video I tear up, not because I didn't know animal rescue was a thing, but because sometimes something just moves you.
Or sometimes if you yourself are going through a hard time, someone doing good can just inspire you. A person I follow on social media has been going through cancer and she recently talked about how a friend did something really simple and it made her cry.
Or as you thought maybe the person for whatever reason wasn't aware that many Jewish people, even many Israelis, aren't okay with what is happening. It's hard to know what's going on when there's so much going on.
There is a lot of really giving and moving stuff in the Jewish faith, but if someone hasn't been exposed to it, it's still easy to dismiss it, especially if someone's understanding of the Jewish faith is more secular, or just the media about Israel, or the more insular versions of Judaism. An extreme example, but if someone's experience with Judaism is the current war and those periodic news articles when some particularly conservative Jewish guy demands a woman not sit next to him on a plane, they might not have the depth of experience you have.
I remember a situation years ago when at a party someone asked i could believe the host had ham given he was Jewish. I said I wasn't aware the host was Jewish and moved on. Later I asked the host about that and he looked at me like I was an idiot saying "my last name is Cohen, how did you not know?" Granted I don't care about someone's religious or ethnic background, but it speaks to my limited exposure at the time.