I thought there was at one time an issue with the fluorite elements in those huge many-kilobuck lenses absorbing moisture from the air and cracking or having ot

I thought there was at one time an issue with the fluorite elements in those huge many-kilobuck lenses absorbing moisture from the air and cracking or having other sorts of failures. Canon for a while stayed with fluorite while Nikon worked out ED glass that avoided the problem. I don't know if today's Canon L lenses use fluorite.