If there is a day where she hasn’t cooked/something is messy you can go and clean/cook in a way of showing that you would also like to help out. Thank her for what she does/show appreciation. Maybe ask her if there is any of the household chores she doesn’t really like to do and maybe if you could take over.
Though, I think as long as you don’t stop showing appreciation for what she does, I don’t think you’ll get used to it. I’m still not used to when my bf willingly takes my bags/luggage when we are out together. (He kinda just pries them out of my hand without a word).
Start taking initiative and clean when she cooks. Starting cooking for her, buying her things when she is low on supplies. She will get sick of being your mother if you don’t do anything in return.
I’ve just spent two years dating a man who let me do all of this, and even though I didn’t directly expect something in return, I didn’t expect him to take it all for granted and completely deny everything for me. He would let me eat shit food in-front of him because I couldn’t afford proper takeout, he wouldn’t even just say “I’ve got your back, what would you like?” or shout me a coffee out without kicking up a fuss. I’m hoping this gives you another point of view.