tl;dr they are shady as fuck

Have experience with working at a company where they (Huawei) had stolen IP.

That, and they give no fucks about following technical standards when trying to bring their hardware to market.

If I could give more detail, I would… but I cannnot.

Suffice it to say - when companies/people don't trust Huawei, there are a myriad of legit reasons for that distrust.

My favorite was when they made linecards with the exact same MAC addresses...

A better question is “Why do entities who aren’t Chinese trust Huawei?”

Understanding that should connect the dots for your other question.

Why do entities who aren't American trust Microsoft, Google , Amazon or apple?

You def shouldn't trust Google, Amazon is somewhat transparent but not great, Apple has said they won't cooperate with the US government in a few cases and MSFT powers most of the business world so you either use them or your business doesn't work.

China != America

Because they started out with stolen US intellectual property and were part of the Chinese state industrial cabal. They basically counterfeited Cisco equipment for years and then eventually started making their own poor quality devices and now make higher end but somewhat low quality devices.

They've also been proven to cooperate with genocidal governments.

This would be a good place to start

https://www.forbes.com/sites/zakdoffman/2019/07/06/huawei-em...

Same reason as Google/Facebook/Twitter being not trusted in mainland China.

It's more about U.S. and P.R.C don't trust each other.