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Dubem, @timclff wrote in the post that some witnesses only give report when they have updates. The witnesses who do not report every week might not really be inactive. Surely, they are running their seed nodes, producing blocks & processing transactions for the steem blockchain behind the scene. The seemingly inactive witnesses might not have steem projects like a few others.

@maryfavour & @redfishpillar.

Thanks so much for the explanation @maryfavour.