Unfortunately, I don't think anyone outside of the founder of Musing and those who might work with him know why they've changed their upvoting activity. The rest of us have been left to wonder what they're doing. As a private dApp on the STEEM blockchain, it's not like they answer to any of us or owe us an explanation. Common courtesy to those who have pretty faithfully been using and promoting their platform would be nice, however.

The last few votes today were on posts by other dApps, sndbox, which has been helping to promote musing through a weekly contest, and steemhunt. My guess is, those four votes are meant to maximize curation rewards, along with whatever show of support to the other dApps they might wish to express, and other reasons they might have.

Prior to this change in upvoting, musing was receiving a substantial amount of SP through curation. That has all but stopped, so I'm left wondering what the plan is for revenue, since they are in need of regularly powering down (even with the larger delegation they had) in order to take care of whatever expenses they were able to with STEEM.

That's about all anyone not in the know can reasonably deduce. That and the real possibility that they have yet to set upon a clear course of action. Or if they have, they're not ready to communicate it yet, since as far as I can tell, there have been no follow up annoucements from jonching, the founder, with anyone in any public place on STEEM or on Discord. Any talking going on in private, I am not privy to.

I believe this question is a very good one, that really should be answered, and sooner the better, but when those who might have the information are silent, for whatever reasons, including not knowing exactly what they want to do yet, I'm afraid there's no way else to know. Hopefully, something will be forthcoming and soon.

As it is, unless musing has some other funding mechanism in the works, not upvoting on a regular basis is not helping their cause.