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-...

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.

Nothing directly, it just sounds bad at face value.