View Transition feature uses a pseudo sub-tree of the element, with ::view-transition being the root of that transition. Previously ::view-transition element was specified to have a position: fixed. CSSWG made a decision to make this instead position: absolute. In effect, this should not be noticeable since this element's containing block remains the snapshot containing block in either absolute or fixed case. The only noticeable change is a change in getComputedStyle.