https://storage.spec.whatwg.org/#ref-for-obtain-a-local-storage-bottle-map states that standards that define a local or session storage type should invoke obtain a local storage bottle map or obtain a session storage bottle map.

We found this confusing in Ladybird, where we are implementing IndexedDB from scratch.

It appears that this issue is known in the w3c community, because it's referenced as Issue 5 in the storage-buckets API draft. https://wicg.github.io/storage-buckets/#issue-4f9abb58

IDBFactory methods need to take a storage bottle map rather than a storageKey.

In the next round of updates, references to obtain a storage key should likely be updated to obtain a local storage bottle map given environment and "indexedDB"

This is extra confusing because https://w3c.github.io/IndexedDB/#dom-idbtransactiondurability-default mentions that

The user agent should use its default durability behavior for the storage bucket. This is the default for transactions if not otherwise specified.

But "storage bucket" and other storage spec hierarchy objects (shelf, bottle, etc.) are not referenced anywhere else in the specification.