Just heard that Kamilla Braylovskaya in Moscow was detained in her school and interrogated by an “extremist case” officer, she has a lawyer since, but interrogations likely to continue. This is a small message to add some publicity to the story.
Kamilla Braylovskaya is the artist from the “Second Headquarters” painting.

Primary sources:
https://www.facebook.com/permalink.php?story_fbid=2174003359547318&id=100008130244041
https://www.facebook.com/permalink.php?story_fbid=1673807776080959&id=100003552589922
Secondary source:
https://www.dw.com/ru/центр-э-заинтересовался-школьниками-с-митинга-навального/a-45571700
https://mbk.sobchakprotivvseh.ru/suzhet/vmesto-algebry/