"Each block should have a 'key' attribute" warning in a paginated {#each} list

I'm building a paginated table in Svelte (Svelte 4, SvelteKit) where a load function reads ?page and limit search params, and the component slices a larger dataset with a reactive statement like $: displayed = allData.slice((page-1)*limit, page*limit). The slice renders through an {#each} block.

When I page through the results, the dev console shows the warning Each block should have a 'key' attribute for items that may change. I understand the warning relates to keyed updates, but my rows contain form inputs and a small child component with local state, and I'm unsure what counts as a stable key when the underlying records can be inserted or deleted between page changes.

My questions:

1. For a paginated slice, should the key be the record's unique ID, or is the array index acceptable given the slice is rebuilt on every page change?
2. Does omitting the key here actually risk stale input/component state when rows reorder, or is it purely a performance concern?
3. If I later switch from offset slicing to keyset (cursor) pagination, does the keying strategy need to change?