Isn't it pretty clear it means "shouldn't exist [under current models]"?

It’s careless language which positions scientific theories as normative rather than descriptive. This makes refinement look like failure (“Science told us things that turned out to be wrong!”), when actually refining theories is progress that should be celebrated.

That's a lot of damage for two words!

Can you suggest an equally terse title that would avoid problems such as "position[ing] scientific theories as normative rather than descriptive" and "mak[ing] refinement look like failure"?

I think you're assigning far too much wrongdoing to this perceived sleight here, I wouldn't even think that saying "our current understanding makes this look impossible" is a way of saying we shouldn't celebrate change and improved understanding, I would instead go the opposite way and think how interesting it is to find things outside our understanding

Why use two words when one is suffient? "Unexpected".

"Shouldn't exist" is cargo cult psuedoscience terminology.

surprising would work for me.

I'm sympathetic to your point, but this usage of should in a non-normative way is also thoroughly colloquial and understood by pretty much any native english. Maybe there is some slight, subconscious coloration, but I can't think of other things which have had a bigger effect on the public's distrust of science than leaving off "according to our best model" from the end of a sentence.

The wording definitely intrigued me, and I understood the implied "given current models". I think sparking curiosity is more important than catering to someone who is not the target audience of a university news article.

Refining theories was banned in 2020 /s.

is there an accepted current model?

To me it implies that the model has more weight than the universe.

I think it demonstrates a sloppy framing of the topic.