What is your approximate location on the earth?

I am in Miami, FL

It looks like frizzle top, caused by a manganese (not magnesium) deficiency. Get a bag of manganese and apply as directed on the package. It takes about 4 months for the new growth to start to come out normal, and some may still come out frizzled in the meantime.

You also need to start fertilizing it with a good palm fertilizer. I'm not sure how to fertilizer palms, so I'll leave that to the experts.

What DG said.... write it down or print it and abide by it if you want your roebellini palms to survive. It can also be extended to include all palms that you can grow in South Florida except the palmetto palm.... Once the new growth s clean and green, quarterly feeding with a good palm food (I have used Lesco brand for many years and it is not cheap, but very good) that has lots of minor elements should be just fine

Thanks, Ben for clarifying how to fertilize them. Our soil is so devoid of nutrients that we have to constantly add them. I find palms to be more work than I desire, but so many people do love them.

Those lady palms behind it look like they could use some fertilizer too.

Thank you both! I've already picked up the Manganese and am hopeful they'll be saved.

I'm very appreciative of the guidance