AI made a large improvement in accuracy on a specific protein dataset. We still don't know how exactly protein folding works. So no, it's not solved.

It did a lot more than that; no, it didn’t “solve” protein folding but for people whose interests are not “work out how protein folding works” it basically removes “solve protein folding” as one of the potential bottlenecks for what they actually want to study.

Turns out that “give a reasonable probability of being close enough such that you can bootstrap a solution out of experimental data” gives a very high utility and effectively obsoleted several experimental techniques overnight; pretty much “Molecular replacement” is about the only technique for phasing resolution anyone bothers with any more.

But again, “Bio” is an _extremely_ broad term; for every part of the field Alphafold had a big effect on there are a thousand different parts of the field that it did nothing for.