automatic price change of ebooks on kdp

That was news to me. Looked at my KDP page, and it says that the pricing changes / royalty changes apply to print, i.e. paperback and hardcover, apparently. The notice was a small banner at the top of my KDP dashboard page.

I guess they need to alter some of the pricing due to increases in paper and printing costs. The notice says price changes aren't mandatory, but it looks like the royalty structure is affected in some way.

KDP is increasing the print costs next month. It doesn't affect ebooks.

For print, if you don't adjust your retail list pricing, your royalty may go down. Note that it may actually go up for certain books. You can see the effects of these print cost changes on your books by looking at the Pricing page for each in your KDP Bookshelf. That page now shows the current print cost/royalty and the future print cost/royalty.