[twotwotwo]

It's interesting this is mentioned specifically about the metadata used by this feature: fingerprinting using this feature has similarities with other cache fingerprinting (wrote a sibling comment about that).

It's not actively bad to have defense-in-depth measures at the level of the dictionary feature. But if your implementation of dictionaries using your browser's existing cache policies is a privacy problem, I'd consider changing the cache, not just the shared-dictionary implementation.