Let's calculate.
Hearties：20×10+17×15+16×20+14×25+14×30=1545=50+150+300+500+545 --(+50)
Snow Fairytale：19×10+17×15+13×20+13×25+10×30=1330=50+150+300+500+330 --(+300)
Savage Bitches：20×10+17×15+16×20+13×25+12×30=1460=50+150+300+500+460 --(+500)
I think it is a BUG. Maybe the power is not cleared when you upgrade.