“What I discovered instead was that the power adapter that comes with the fountain outputs a solid 7.5V.”
The Catit Flower Fountain ships a USB type A power adapter that measures 7.71V. Real USB type A ports top out around 5.25V. Two power banks plugged into it started glitching afterwards. Catit saved a few cents on a barrel jack and turned a standard port into a trap for anyone who charges a phone from it.