прокладка

Russian

прокла́д(ывать) (proklád(yvatʹ)) +‎ -ка (-ka)

Senses 5 and 6 refer to the protest flags' similar appearance to a menstrual pad.

прокла́дка • (prokládka) f inan (genitive прокла́дки, nominative plural прокла́дки, genitive plural прокла́док)

laying, building, construction (of roads, pipes, communications, etc.)
packing, lining, gasket
sanitary napkin (US), sanitary towel (British)
(derogatory) a fraudulent business that steals money from customers
(politics, slang, derogatory, offensive) the white-red-white flag of Belarus, formerly the national flag, used to protest Alexander Lukashenko's government
(politics, slang, derogatory, offensive) the white-blue-white flag used in Russia to protest the 2022 invasion of Ukraine

Declension of прокла́дка (inan fem-form velar-stem accent-a reduc)

	singular	plural
nominative	прокла́дка prokládka	прокла́дки prokládki
genitive	прокла́дки prokládki	прокла́док prokládok
dative	прокла́дке prokládke	прокла́дкам prokládkam
accusative	прокла́дку prokládku	прокла́дки prokládki
instrumental	прокла́дкой, прокла́дкою prokládkoj, prokládkoju	прокла́дками prokládkami
prepositional	прокла́дке prokládke	прокла́дках prokládkax

БЧБ (BČB) (former flag of Belarus)
БСБ (BSB), бе́ло-си́не-бе́лый (bélo-síne-bélyj), автоза́к флаг (avtozák flag) (anti-war flag in Russia)