It's important not to shift the goalposts. Western security establishments are concerned that once Huawei has overwhelming marketshare in systems like 5G networks, they will have the ability to use these against target nations. They (at least the credible agencies) are not claiming that current Huawei devices are backdoored now.

Even if you believe the worst about China and Huawei, it wouldn't make the slightest bit of strategic sense for them to implant backdoors into products now, when marketshare is still small and growing rapidly. You'd add the backdoors once you had network dominance, like the US did.