Most good scientists work hard to prove results to themselves before going public.

Peer review is then done _in private_ before publication as a check on quality and significance.

Retracting a paper is pretty embarrassing. And not considered science as usual.

The greatest proof ever written by man, Andrew Wiles' FLT, was published with a flaw before being retracted and reworked. It's _completely_ normal in mathematics to find flaws in the argument. That's what peer review in mathematics is _for_.

Besides which it's not clear if these papers are considered published or preprint since they appear in no journal, so it's not really a retraction.

It's also very very normal to post preprints on Arxiv before peer review, so it's not the case that mathematics is kept private during review.

Retraction is after publication and peer review, no?