So, I get why it has become unacceptable for White people to darken their skin to impersonate Black people (it became impossible to make a somewhat fuzzy distinction between racist and non racist instances of this practice, and there were so many bad faith actors in that space that it was easier to start saying that all instances of skin darkening by white people was racist).
But I think it is unfortunate, for several reasons, not least that it has tended to erase and trivialize what blackface really was and is. Blackface involved not just skin darkening, but doing it in an exaggerated way, often with other exaggerated features, in an explicit attempt to make fun of, demean and dehumanize Black people. It was in the service of maintaining the racist hierarchy and justifying and enforcing racial injustice and violence.
Billy Crystal blackening his face to do his Sammy Davis Jr impression is not “Blackface”, indeed it was the opposite, a clearly affectionate and respectful homage. I’m not sure when the last time he did it, but he wouldn’t do it today, not because it is racist, and not just because he would get “canceled” but because as innocent as it is, it gives cover to actual racists who would do blackface and use Billy as an excuse. Racists are why we can’t have nice things.
That said, I can easily imagine that a Polish guy in darkened face spitting the N word in a Kendrick Lamar song would actually be more of the toxic blackface variety.