If it's okay for Corporations can run ads themselves, then your objection isn't to wealthy people supporting candidates or even them doing so secretly, but... only when the little guy pools donations and they happen to be pool donations via a corporation?
I'm against anything secret about spending on political campaigns.
Candidates should only accept funds from natural persons, that amount should be limited per person.
PACs and other candidate-adjacent activities should require 100% transparency on the source of funds and not be allowed to co-operate/co-ordinate with any candidate's campaigns. Companies can fund PACs, but they should be required to receive shareholder endorsement and not co-ordinate with their employees.
Laws impacting on the 1st amendment require strict limitation on how the government legislates and for an explicit need.
In this case, it is to ensure the integrity of the political process of selecting candidates and electing members of Congress.
If it's okay for Corporations can run ads themselves, then your objection isn't to wealthy people supporting candidates or even them doing so secretly, but... only when the little guy pools donations and they happen to be pool donations via a corporation?