You are confusing state policies with the State makeup and using an absurd version of the definition. The important facet of its definition is the peoples it identifies with are not associated necessarily to citizenship.
When the Russian government blames an invasion on russian peoples (identified solely by their language and culture) being mistreated in other countries they are an Ethnostate. If a nation welcomes its diaspora back and assures their citizenship solely based on their being the same peoples, they are an Ethnostate (most all the other nations I’ve listed) and it is reasonable to see that this definition holds whether they are 100% successful or not.
When you agreed that “All ethnostates should be dismantled” which ones came to your mind?
I’ll only bring this up because you mentioned being American, that the US is actually on the precipice of becoming an Ethnostate based on common rhetoric used in their politics (American is becoming a cultural identity independent of citizenship).
I have not said anything that argues what is happening over their needs to continue. Just that I’d also take issue if you were arguing American Politics is immoral and so democracies need to be dismantled.