“Objects can be reordered any number of times without leaving any additional information behind.”
Give every item a fraction between 0 and 1, insert new ones between their neighbors, and add a little random jitter so two peers don’t collide. No tombstones. The catch is that concurrent inserts can interleave, so it’s fine for photo albums and wrong for text. The Figma co-founder explains in one page what most CRDT papers bury in twenty.