I'm seeing Ukrainians using yellow/green tapes while Russians are using white/red. Russians are also painting 'Z', 'V' and 'O' on their vehicles. Z being from Russia and V from Belarus.

I was wondering what the Z meant and after searching other people would too, and there were multiple theories. One of it was that Z stood for the main target - Zelenskyy. But that was just as likely as the other theories, but now that you said there are also V and O do it is for his full name: Volodymyr Oleksandrovych Zelenskyy then that's def it.