I'm not from the Musing team but I have been a user of their platform for over a month now and have been here even before they received the 350k+ delegation from Steemit Inc.

One thing I noticed is that the Musing team really did try to give everyone decent significant rewards for the contributions made to their platform while making sure that their Voting Power do not drop below 80%.

I suspect that the decrease in upvotes you noticed is mostly related to this. Upvotes are usually done in batches and when their VP is near 80% it seems they are giving less than what you normally get.

Of course this can also be attributed to the huge influx of new users on Musing as it is now harder to scale the voting weight while still trying to give a decent upvote worth.

So yeah I think it is both, increase in threads and Voting Power healing. :)