It's not an internal affair for crap-hole states like MI, PA and WI among others to violate the Constitutional requirements that the legislatures determine how the state's electors are chosen for the Electoral College.
Which means all the normal states had the right to sue when those crap-holes stole the election.
I agree, in that for the hanges to election law to be legitimate, they must come from the respective legislatures of those States, by the constraints of the Constitution. In the instances of MI, GA, PA, and others, those changes did not emanate from the legislature but were designed and implemented by (partisan) bureaucrats and judges.
On the face of it, this tramples the separation of powers, in that executive and judicial branches of those respective States, sometimes pretty far down the pecking order within their respective venues usurped the power of those respective legislatures and, in doing so arguable changed the nature of an election which affects us all.
In that regard, certainly Texas (and the other States which joined in) has a legitimate Constitutional complaint, and by virtue of being affected by the outcome of that election (VIZ: the 'surge' at the border, for one thing), those states certainly can show injury, and thus have standing.
You don't have to be a IV League Constitutional scholar to figure this out, and the effects of announced intended policy were entirely predictable. If the question was merely a matter of waiting until injury was sustained, we're already there.
The Supreme Court, by virtue of the same Constitution which delegates the crafting of election laws to the various State Legislatures, is THE court of primary jurisdiction.
Such cases between the States or one State and other States start and end there.
In the abdication of their Constitutional
responsibility DUTY to rule on this matter, the SCOTUS has, itself become in violation of its sworn duty to uphold the Constitution, which begs the question of whether any ruling henceforth can be taken as legitimate.