Well, you could say they both "lost" the spot that year (2018). Nastya G. because she was 4th at JNats, and according to the opinion of many, she should've been 3rd. In fact, the final difference between 3rd/4th was around 1 point. Stasya recieved just enough in the fp to overtake Gubanova's sp advantage (IIRC Stasya had had some error in the sp). Nastya T. "lost" the spot because she was 3rd at JGPF (in addition to having won a JGP), and skated cleanly at nationals IIRC, although only placed something like 7th, but the difference between 7th and 3rd was only 8 points, so you can see where the controversy was. Either way, many considered either of them more worthy than Stasya. Heck, even Anna Shcherbakova went on the win the RCF, beating even Trusova with one quad landed, which was still before junior worlds, and some thought even she should be sent over Stasya. In addition to that, you could say that Gubanova also "lost" her spot in 2017, as she had placed second at the JGPF but wasn't named to the junior worlds team, although admittedly Stasya was second at junior nationals while Nastya G. was 7th and I have no idea how anyone performed that year at nationals and if those places were "deserved".