Known limits

A loop copy renders the slide's children again. Their state is their own, effects and refs in them run once per copy, and an id inside a slide repeats three times. Avoid ids in looping slides, or make them unique outside the slide. Deck.useSlide() tells content whether it is in a copy.
Presses beyond the reachable copies are dropped. A step goes at most a set of copies past either end. When presses come faster than the deck moves, the deck passes fewer slides than were pressed, rather than moving against a press or jumping mid-motion. At rest, a press always moves it one snap point.
Fade ignores slide geometry. Slide width, alignment and pages do not apply to a fade deck.
Curve draws on the slides' children, not the slide box. A slide's own background and border stay flat.
Server HTML can only start at a slide. With several slides per snap point, or pages, the first paint at a defaultIndex may correct after hydration, and Dots and Counter recount.
The first paint estimates progress from the slide's index. Server HTML gives each slide its distance in slides from the starting slide. With slides of different sizes, pages that start past the first, or a start the scroll range keeps from the focal position, as at the end of a centred deck with no padding, an effect or CSS on progress can move slightly at hydration, when the engine measures.
A controlled index counts pages. A breakpoint that changes the page size points the same index at different slides.
A long task can let Chromium undo a wheel. When a long task holds the main thread just after a wheel during a move, Chromium can carry the move on to its slide, against the wheel. The deck still rests on a snap point.
No automated test covers touch flicks across a loop's seam. The maintainer checks them by hand on a phone and a trackpad.