I’m a little confused by this and maybe I’m missing something. Wasn’t localStorage always intended to be treated as a volatile storage mechanism for non-critical data and caching? The advice I’ve seen for several years says to avoid storing sensitive or critical data there.

Can PWAs not switch to using IndexedDB which seems like it’s more purpose-built for this use case?

No snark intended. I’m legitimately curious what the situation is and where any blockers are.