What's the problem with stock buybacks?
They are nothing but direct stock manipulation that was 'legalized' at the same time where executive compensation was moved from salary to... stock, so that you end up with a quasi-legal (stock manipulation by executives is supposed to be illegal) corrupt incentives system.
Couple articles that explore that:
https://hbr.org/2020/01/why-stock-buybacks-are-dangerous-for...
https://www.theatlantic.com/ideas/archive/2018/07/are-stock-...