synapse always includes redundant m.room.member events for most endpoints with lazy-loading enabled

[richvdh]

as per

synapse/synapse/handlers/pagination.py

Line 262 in e26e6b3

# TODO: remove redundant members

[ShadowJonathan]

Up-to-date line from #11960;

synapse/synapse/handlers/pagination.py

Line 549 in dd2d66b

# TODO: remove redundant members

And, related spec issue: matrix-org/matrix-spec#942

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Also worth mentioning that, because synapse always included redundant members, it caused some problems when redundant members were removed in other (spec-compliant) server implementations, due to the default expectation of synapse's behaviour;

• https://gitlab.com/famedly/conduit/-/issues/233
• No avatars or displaynames when scrolling up (Conduit) element-hq/element-android#3417

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Likely relevant is a previous comment from @erikjohnston:

First step is to figure out what is required to actually fix these TODOs, note that there are likely other TODOs around lazy loading of members in the pagination and sync code.