Kamila Valieva is a 15-year-old who lives and trains within the controlled cocoon of the Figure Skating Federation of Russia. As such, most agree, she probably did not independently obtain a drug for angina patients that just happens to improve endurance (and is thus banned by the World Anti-Doping Agency).
So when that substance, trimetazidine, was found in Valieva’s system, it's assumed that some coach, doctor or whomever in Russia is responsible for the skating sensation being hopped up on heart pills.
This is the same Russia, of course, that ran a sophisticated, state-sponsored, performance-enhancing drug operation at the 2014 Olympics, causing the IOC to ban it from three subsequent Games, including the current one in Beijing.