Maybe SU is suffering from "low ratings" because idk they started regular schedule broadcasting in the worst time ever. Like for me I'm back in college and now I live on campus so I'm stressed by that. *This was not meant to sound snarky or rude*
Everyone’s viewing situation is different- and with a show like Steven Universe that appeals to a considerable range of age groups, I wouldn’t say your situation is the tipping point necessarily for a lower trend in ratings (which to be clear, there is no dipping point in ratings currently- SU’s ratings are fairly average in comparison to other series currently on air with similar viewership).
It might feel like it’s less prevalent currently for some, which in my experience is when people tend to worry/whine about ‘ratings’ but maybe that’s because it’s just not central in their everyday lives and conversations like it might have been before- and that happens! There’s lots of stuff that can occupy you in a day/week/month/year and it isn’t always going to revolve around the media you enjoy and that’s just how life is.
Steven Universe in terms of just core numbers and general online trends is doing very well, there seriously is nothing to worry about for the series future as far as I, an average viewer and casual observer of TV trends, can tell.