Tupperware after you put spaghetti in it

https://lemmy.world/post/3402897

Tupperware after you put spaghetti in it - Lemmy.world

Can anyone explain why this happens. Bonus points if you can tell me how to remove it.
Oil/grease + tomato. Dawn.
This reads like a word puzzle, with the random mention of dawn at the end. What’s the time of day got to do with it xD We’re washing containers not casting a spell :-P