I don’t know about the others or how they come about, but this one is grounded in history. As far as I know, Huawei begun life as an OEM producer for Cisco, at the early stages they copied Cisco designs, hardware and software, and produced knockoffs branded as Huawei’s own to make more money.
At the time Huawei didn’t know there were backdoors in the software since they just copied Cisco one for one, we are talking really early stages where Chinese knowledge in IT was basically non-existent. So when the US accused Huawei having backdoors back in the day it was actually true since Cisco had backdoors. I guess they have just continued the same accusations ever since.