I was fine with Toffee being killed off in itself because I generally liked Battle for Mewni, but seeing how S3's gone since then, yeah, maybe that was a mistake.
Or more like, since Toffee was probably always planned to be killed off that way, maybe we never needed S3 (and beyond) after all. Just wrap S2 up with BfM as the series finale, change a few things so that Heinous's relation to the Butterflys is addressed somehow and Starco happens that season (not because I want it, but because they were obviously going that route as soon as My New Wand).
It's weird that we've known about S3 when all we had was S1, and now I'm regretting they got one at all. S2 just felt planned out so much better (with BfM as the obvious S2 ending), and while I'm sure they have a plan now too, it's neither as interesting nor executed as well as the show once was.