I don’t know what it is with kids and drawing on walls but every single one of my little artists did it. I got tired of always touching up the walls so I got creative. When Peter and Esther were younger I painted one of their walls with Dry Erase kit which I purchased at Home depot. I had a tin can of dry erase markers nearby. Costco sells them for a good price and they come with so many different colors. My kids often times forgot to close the lids on the markers so I started to buy our dry erase markers at the dollar store. Make sure you get the markers that say low odor on them otherwise the smell is too strong.
You could also paint the door of your kids room with the dry erase kit. This white board wall helped me save a lot of paper and my little artists did draw less on the other walls.
Have fun 🙂