прапор автозаку

Etymology
From. Named due to the similar colours between the flag and the police vans' blue stripes. Compare 🇨🇬.

Genitive ending -у may have been used by analogy with declension of country names (e.g. прапор Бангладешу) or collective nouns (thus meaning flag of all autozaks/police vans).

Noun

 * 1)  The white-blue-white flag used in protests within Russia against the country's invasion of Ukraine.