Is the blackfaced actor used to make fun of black people? Probably racist. But that would also be the case if it were a black actor doing the same (it might just be more difficult to hire one for that).

Is it used to create tension between the obviously fake costume and the effort put into pretending that it is real? Probably not racist. I can imagine a show deriving great hilarity from casting everyone in a role they are not the least bit suited to and then trying to make it work anyway.

Are there people from Japan, or Somalia, who many Russians (and the newspapers) would unthinkingly refer to as Russian? (Not a rhetorical question!)

I guess my criteria (for the above) are something like this: an awful lot of British people, and 100% of newspapers, will describe the sprinter Sir Mo Farah as being British, and only get to his place of birth on page two. This pretty much doesn't happen elsewhere.

Although a reverse thing does happen, in which (for example) 2nd- and 3rd-generation british indians are not only welcome to almost all the privileges of Indian citizenship, but (if they become famous) are cheered in India. There is a lot of fawning over Priti Patel in the Indian newspapers, but obviously none at all in Ugandan newspapers.