Beyond what they had already done in the extremely small scope of making Twilight interesting, giving Twilight the "Super Saiyan God" method of extreme power up was basically huge character decay for Twilight in the long run. Since she's no longer as interested in the wizarding or science aspects of her magic, she's basically left with her most basic alicorn powers. That combined with the transfer method amping up her magic to the 11th power, in a season finale that wasn't the end, basically doesn't give Twilight any room to grow. In terms of strength, her character is sputtering.Stopping a unicorn's magic or struggling with a worm monster are the extent of her unaided strength currently, and I can honestly say Twilight was a lot stronger in earlier seasons when she had a lot of gumption to match her early uncertainty.That's definitely part of it, but I think another aspect is the confusing long character arc they've taken with Twilight, with Amending Fences being one of the big turning points.