I can see why you’d interpret it that way. My bad for not being more clear. To clarify, here is a timeline of how I think it went down:
October 5, 2019 - Despite running an American record, Shelby fails to medal in the 1500 final. She is (understandably) furious because she believes she got robbed of a medal by dopers.
July 10, 2020 - Shelby runs 14:23 and breaks the US 5,000 record. She’s proud to get the record but also frustrated because she’s still not as fast as the top East Africans. Three runners ran faster less than a year before at the London Diamond League.
October 7, 2020 - Letesenbet Gidey smashes the world record with a 14:06. Shelby is apoplectic.
Gidey’s ridiculous WR was the final straw for Shelby. She thinks: How on Earth can she compete with the likes of Kipyegon, Hassan and Gidey without doping like she believes they must be doing? This is when she finally crossed into the dark side.
December 15, 2020 - Shelby tests positive