First of all, I am not on twitter, so I don't actually know what I am talking about.
The problem is they don't say what is being verified, just that it is verified.
As I understand it. the verified tag means(or used to mean) that a twitter account claiming to be a person of certain infamy is actually that person. however there is no additional information as to exactly what the verified cv for this person is.
I would have expected, at minimum, something like certificate authority verification. and twitter could make a claim like(all examples are fake). @cmarc239 is verified to be the youtube channel "couriusmarc", @will_i_am is verified to be sony_music/blackeyedpeas, @joebiden is verified to be jbidon@whitehouse.gov or @rprwins is verified to be the twitch account m_rpr_actual