Maybe for spying, maybe because QA failed.
Huawei is on the US radar but somehow when Cisco left a backdoor on some routers it was "just a mistake".
Every country is guilty of stabbing in the back others (occasionally or all the time), it has been the case for centuries and is not likely to change.
I am French, we do not have our own tech so we get stuff from everyone around - we are probably in the worst spot from that perspective.