I see a lot of LP collections with the records leaning to one side. As @dseltz just said, given enough time LP’s thus stored can become "dish" warped.
I years ago came up with a solution: you know the cardboard "spacers" you routinely find inside the mailing cartons your LP shipments arrive in? Don’t toss ’em, keep ’em and use them to take up the empty space in each section of your LP shelves. Doing so keeps the LP’s perfectly vertical, and one spacer can be removed for every new LP that needs to go in that section.
Record stores receive one or two spacers in each carton of LP’s they are shipped; ask your LRS for the ones they routinely recycle. I have two linear feet of them!