What does being ethnically Russian have to do with the language? Ukraine is perfectly fine with people who were born in Soviet or post-Soviet Russia

Except if you speak Russian then......well not so much now right? But this is also nonsense if again Canada banned French in schools and government institutions it doesn't matter if someone like Céline Dion is beloved when normal people are negatively impacted by their protections being taken away. Do you think that some 50-60 year old ethnically russian person that maybe learned ukrainian as a school kid but since they never used it again or not often enough doesn't really speak ukranian anymore and now has to go to their municipal offices to renew some permits or their passport or whatever and they are shit out of luck because Poroshenko did away with all of that because he was and presumably still is a far right nationalist.

Again while the latter is not outlawed when you pass laws that clearly do away with protections and you not so subtly say 'You know it's ok to be cruel to those people' then people will be cruel, like look at the USA currently under Trump where a lot of people are a lot more comfortable being cruel towards minorities.

But hey let me just quote a part the European Charter for Regional or Minority Languages:

Part II of the Charter

Recognition of regional or minority languages as an expression of cultural wealth.

Respect for the geographical area of each regional or minority language.

The need for resolute action to promote such languages.

The facilitation and/or encouragement of the use of such languages, in speech and writing, in public and private life.

The provision of appropriate forms and means for the teaching and study of such languages at all appropriate stages.

The promotion of relevant transnational exchanges.

The prohibition of all forms of unjustified distinction, exclusion, restriction or preference relating to the use of a regional or minority language and intended to discourage or endanger its maintenance or development.

The promotion by states of mutual understanding between all the country's linguistic groups.

Protections of minority groups is again like one of those things most nations and people agree on this isn't radical stuff because if those existing protections are being taken away then it's often a one way trip to ethnic repression which unless drastic measures are taken to put them back in will inevitably lead to mass killings or worse.