The government illegaly passed a law banning civilians from wearing helmets, so that the protesters couldn't protect themselves from the batons of riot police.
Ukrainians therefore started wearing metal pots on their head to mock these laws.
You say that, as if "beeing historically close to Russia" is a good thing. Let's review: systematic prohibition of Ukrainian literature and theatre during Tsarist Russia, the famine genocide in the early 20th century, Ukraine bearing the bulk of the damage during the Nazi occupation, just to name a few. Oh, THANK YOU, Russia! Could we please have some more exploitation?