Who recently lost out on a Worlds or Olympics medal because politics weren't in their favor?
It's not simply a matter of 'losing out on a Worlds or Olympics medal.' It's a matter of the deeper talent in the ladies field from a number of countries, plus endemic politics, and the post-2014 Olympics fad for rotating* baby ballerinas complicating the chances for good performances by some U.S. ladies to be better rewarded.
*LOL, 'rotating' in more ways than one.
There were some World championships where both Ashley and Gracie performed well and arguably could have reached the podium if politics had also been in their favor. In terms of some other competitions, there were discussions about how Mirai and even recently Bradie were short-shrifted in the marks or wrongly judged on UR calls. Politics and fed clout are huge factors. A lot goes into judges' thinking and impressions about skaters, including fed clout, political conflicts of interest, skaters' recent performances, reliability of skaters which is about rep level, in addition to the over-attention placed on multiple rotations. Complete performances and artistic sensibilities count for less. Lack of maturity and experience is not important at all in the current ladies' environment, as long as you can quickly rotate and land with some consistency.
The judges even ignore technical execution deficiencies once a skater has obtained premature recognition, e.g., Olympic champion Alina Zagitova who IMO was over-rewarded for her labored crossovers and so-so PCS skills. She's a talented jumper and a worthy athlete with a number of strengths, but also a number of weaknesses that were overlooked in the rush to reward her Eteri-style performance gimmickry and jump backloading. Post-Olympics, Zagitova struggled in her sophomore senior season for a number of reasons. She finally made a push to at least be consistent enough for the judges to purpose-reward her a World championship. As a result, Zagitova and the judges could breathe a sigh of relief about the Olympic medal win not being the fluke it actually was.
If they were going to give the 2018 Olympic medal to a Russian lady, and that outcome was preordained, then it should have gone to Medvedeva, who'd at least paid her senior dues for more than a brief season, not to mention toughing out a difficult Olympics. But maybe things happen for a reason. In actuality, the bronze-place finisher, Kaetlyn Osmond, was the better overall skater among the top three. Sadly, Osmond was for good reason not seen by the judges as a consistent performer under pressure, even though without question she was the better jumper and the better all-around skater with a gorgeous program. Winning Olympic bronze was a victory for Osmond, which she later backed up with a deserved World championship win.
It just so happens that U.S. ladies still have a great deal of talent (if not more talent than ever), but today they are no longer supported by the political and television contract clout the U.S. federation used to hold. The international ladies field today is chock full of talent and pressure-filled expectations. It's not like the old days when U.S. ladies were always in the mix to win a medal due to huge talent, as well as favoritism politics. But even in the old days, some U.S. ladies got the short end of the stick in certain battles, e.g., Sumners vs Witt, and Fratianne vs. Potzsch.
Interestingly, even with going 10 years without a World or Olympic medal (aside from Wagner's World silver in 2016), the U.S. ladies' discipline still holds the record for total World & Olympic medal counts (U.S. ladies especially dominated beginning in the 1950s through 2006). It will still take Russia, Japan, and South Korea a number of years to catch up, though ladies from those countries have been gaining ground.