It appears that it is indeed being passed by kissing. The outbreak in Europe started in two raves where people were making out on the dance floor.

"Face to face" contact is known to spread monkeypox.

I suspect we will find this is not a new adaptation, but the result of people who have been not partying because COVID now deciding the COVID risk is low enough to go out partying and kissing strangers again...and by sheer chance, whoever it was at the rave who had monkeypox and didn't know it was gay. It should be controllable with ring vaccination (which is where you vaccinate the person's household, healthcare workers that have to care for them, etc) rather than needing mass vaccination. We have more than enough Jynneos to do that.

Obviously, I could be wrong, but this appears to be a controllable disease, with extant vaccines that we can use. I doubt it's going to go pandemic on us. That doesn't mean people shouldn't take appropriate precautions, and if you are the kind of person who's partying includes snogging strangers on the dance floor, you should probably be careful. (Note, I don't judge people who snog strangers on the dance floor, I might have done it a couple of times myself when I was young and single, although it taught me that I don't really want to snog strangers on the dance floor ;)).