The Russian skating federation announced the news on its website on Monday (13 December), saying that Kostornaia was injured, but offering no further detail.
The national championships are set for 23-26 December in St. Petersburg.
The full ROC Olympic team announcement is not expected until the European Championships, set for 10-16 January in Tallinn, Estonia, but Kostornaia's absence at nationals will certainly impact her path to Beijing 2022.
The 18-year-old had a golden season in 2019-20, sweeping both her Grand Prix assignments and the Grand Prix Final, as well as Europeans. The world championships were cancelled weeks later, however, and Kostornaia has had several challenges since, including changing coaches twice and contracting Covid-19, the latter forcing her to miss nationals in 2021, as well.
She placed third at Skate Canada International and second at the Internationaux de France this season, each time finishing behind Russian teammates. She had qualified for this month's Grand Prix Final in Japan, but that event was cancelled due to fears surrounding the omicron variant.