Example from Networking Hardware:

Cisco has had multiple cases where they likely built exploits for Government spyware into their devices. And they have far to many vulnerabilities which are found. This leaves two options: Either their security is so bad that intelligence always has backdoors ready and governments shouldn't use them, or at least some are backdoors built in accordance to NSA demands and goverments shouldn't use them. https://thehackernews.com/2016/08/nsa-hack-exploit.html?m=1

On the other hand Huawei, far less security issues, even offered to open their code for checking of backdoors and to let goverments check all updates. They are shunned by western governments and partially even banned.