Folic acid is not folate

www.ukflourmillers.org/knowledge-hub/standards-regulations/bread-flour-regulations/folic-acid

dailybread.co.uk/about-us/daily-bread-blog/folic-acid-in-flour-what-is-changing-and-which-flours-are-affected

www.gov.uk/government/publications/folic-acid/folic-acid

My Dh was given folic acid as part of his chemo regime, to counter some of the unwanted side effects.

I've been taking folic acid on prescription for nearly 20 years with no problems.

Spina Bifida is a dreadful thing where the backbone does not develop properly round the spine because of folic acid deficiency in early pregnancy often before the mother even knows she is pregnant.
That is why it is added to flour in very small amounts so that spina bifida is prevented.
There is no cure only treatment.

www.nhs.uk/conditions/spina-bifida/

Flour ‘fortification’ chalk supply presents a risk to the UK food system
www.sustainweb.org/blogs/dec24-flour-fortification-chalk-supply-presents-a-risk-to-the-uk-food-system/

I think it's very difficult to overdose on folic acid and you can avoid it by eating wholemeal bread tbh I'd be more concerned about the additives that are put in to help factory production and the preservatives to keep it from going stale. We make our own bread using a bread maker, use decent flour, nothing else is added except the basic ingredients. I make sourdough by hand and that's the same. Sadly not everyone has a good diet and if adding folic acid to white bread flour stops some babies from being born with spina bifida, then I think it's an acceptable risk.