We don't yet know who initiated the break up and the reasons they gave.
Coach unsatisfied with the performance of her ward,
skater unsatisfied with the coaching she received?
I think we can agree on the observation Stanislava has had a dramatic season and sunken into a depression.
Her position on the national selection might even be in jeopardy given the revised criteria recently published.
More first hand news probably in the local Piter press, unless SE etc. have a better lead.
I don't get the idea of moving to a 'lesser' coach is considered a degradation. A good, positive and productive working relationship is more imporant than keeping up appearances.
FFKKR by Kogan declined any comments since they don't know anything more:
"he Russian Figure Skating Federation does not currently have information.
“We do not have such official information yet,” said Aleksandr Kogan, FFKKR's General Director.
In the season 2018/2019, Konstantinova took 4th place in the Russian Championship, beating Alina Zagitova. Then she became fourth at the European Championships.
This season, the results of 19-year-old St. Petersburg dropped. At major competitions, she did not comply with the standards for joining the national team: 11th place in two stages of the Grand Prix and 13th place in the Russian Championships.
The last chance to save Konstantinova in the Russian national team is getting into the Top-5 finals of the Russian Cup, which will be held from February 18 to 22 in Veliky Novgorod."
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From:
https://www.sportsdaily.ru/news/stanislava-konstantinova-ushla-iz-gruppy-chebotarevoj
Meaning she is most likely out.