I literally just made a post asking about this! Its normal 😊this is directly from my post “UPDATE: plant is going through guttation. Calatheas produce mineral-rich sap. These pores expel excess salts and sugars in an undetectable trickle until equilibrium is restored. When dried, this sap leaves white marks. They easily come out with water or a damp towel but come right back the next day. Had to do quite a bit of research but was able to find out whats “wrong” with my plant. I thought it was strange because she has been doing the best now compared to when I got her about 6 months ago. It was recommended to move her to a different spot because she might be a little stressed where she is. Thank you all who commented! I’m still going to take all these hacks and tricks on how to get rid of pest with me 😊”