They changed the law regarding multiple citizenship. Or rather actually wrote it, since it wasn’t really legally defined prior.
Multiple citizenship (subjectivity) is not allowed in cases of registration of acquisition of citizenship of Ukraine or acceptance into citizenship of Ukraine, or renewal of citizenship of Ukraine in respect of a person who is a citizen of a state recognized by the Verkhovna Rada of Ukraine as an aggressor state or an occupation state, or a state that does not recognize the territorial integrity and sovereignty of Ukraine, or refuses to recognize the illegality of encroachments on the territorial integrity and sovereignty of Ukraine, in particular, voted against the resolution of the General Assembly of the United Nations
They changed the law regarding multiple citizenship. Or rather actually wrote it, since it wasn’t really legally defined prior.
https://ukranews.com/en/news/1053462-rada-wants-to-introduce-multiple-citizenship-in-ukraine