Can you provide an example?
https://www.wsj.com/articles/amazon-tech-startup-echo-bezos-...
When I worked in startups this was long rumored with little proof. After years it's become quite clear what's happened.
Amazon Show is a knockoff of a Nucleus (https://www.vox.com/2017/5/10/15602814/amazon-invested-start...)
Amazon Echo https://gizmodo.com/did-amazon-rip-off-the-echo-show-from-a-...
This trend goes on