Alternatively, "it has yet to be proved mathematically".
1. pedantry
We only have a few of these in English, where one of the tenses of the verb changes depending on the subject matter, but they do exist. The only other one I can think of off the top of my head is hang: past and participle "hanged"/"have hanged" (to execute or be executed via hanging from the neck) versus "hung"/"have hung" (any other meaning).
Hope that helps!
Edit: fixed my example to better match the original text.
I'm not a mathematician though, so maybe this is a genuine semantic convention that neither I nor my dictionary are aware of. Maybe it's just that some mathematical style guides say to prefer "proved", for consistency, not that it really depends on the context?
It feels sort of like the difference between gilded and golden. Something that has been gilded now has a golden surface. Now golden has that en suffix like some participles, but isn't one. It's a pure adjective.
You don't say "your application has been approven".
Or "the problem has been solven".
Or "the quantity halved again, like it had halven before".
Or "that function has misbehaven again".
Or "I have moven the funds to the correct account".
Yet, "proven" is accepted.
Same with: write, wrote, written; smite, smote, smitten; bit, bit, bitten; hide, hid, hidden; ride, ride, ridden; drive, drove, driven.
There's a pattern that the verbs with the en participles do not have ed regular past tenses. They have ove, ote, ode, it, id past tenses.
There are exceptions though like swell, swelled, swollen. It's fuzzy enough that any -en past participle will sound fine if you just get used to hearing it.
"Proven" refers to something confirmed over time, often used more informally.
"Proofed" is an editorial term—preparing text for publication.