In close to 40 years of growing, I have never seen anything like it, but it is fascinating and a bit beautiful.....
Pretty sure (99.9%) it is not a deficiency of any sort, but my guess is that it may be a fungal problem of some sort, but not really sure about that, so no real help to you either.
Looks quite pretty though.
Not sure what to do, but if your plant is and keeps growing normally, ignoring it and hoping it goes away might be an option.
Definitely taking a screenshot of it and adding it to my files!