They were banned way back when the Geneva stuff started. That’s why we never see them post-ACW.
Damn shame. Nothing scarier than an 18-in multi-blade through the body.
I hear the Geneva stuff often, but it is hard to pin down.
https://www.reddit.com/r/AskHistorians/comments/13b8zt/triangular_bayonets_banned_disliked_or_what/
The triangular form of bayonet was developed simply for ease of production combined with strength - a three-sided blade being stronger than a two-sided, flat blade and using less material. The triangular blade causes no more blood loss than a wound made by any other bayonet of comparative size.
The screwdriver point, mentioned in this thread, was developed to easier penetrate bone than a sharp point.
For further info check out my book “Guide to Bayonets of the World” at http://www.wbdpublications.co.uk/11-bayonets/index.htm