The Constitution confers upon the legislature of each state the power to direct the manner in which the electors are chosen.
That being the case, why is it that the state’s executive branch certifies whether the electors were chosen legally? If the electors were not chosen according to the manner in which the state’s legislature directed, then the Constitution has been violated. - specifically, the US Constitution has been violated.
Potential violations of the US Constitution are the purvey of the United States, not just the state in which the violation occurred.
In my particular state, the legislature gave the executive branch a wide range of oversight authority and powers to do exactly that.
That’s why I said from the start (September-November 2020) that the legislatures in all the contested states should have convened and set their own clear ground rules to deal with the overreach (as I saw it) of their executive branch officials.