The US considers China a rising rival.
In the case of Huawei there were 3 major factors to it being targeted:
Political
Clearly, the previous US administration made a big show of "standing up to China" and Huawei was a convenient pressure point. Claims that Huawei bypassed sanctions to Iran, which is the core of the Meng Wanzhou extradition case only added fuel to this.
Economic/commercial
Huawei was at one time, rising quickly in 5G networks and the top Android smartphone vendor. Being associated with China, rather than an ally like Samsung's South Korea made its dominance unwelcome.
Security/military
5G networks, whatever their current benefits to users, are the future of cellular phone technology, at least until 6G comes out. The US, not incorrectly if one considers China a potential military rival, was not keen on having its networks and those of its Western allies largely supplied by a Chinese vendor which was putting Western suppliers out of business (by having better, cheaper, gear).
GHCQ in the UK did an audit of Huawei's code (and hardware?) and didn't find all that much, except that it didn't seem very well written (all is relative, telecoms people tend to make fun of practices of certain Western network vendors as well).
GHCQ not finding anything may or may not mean much, but recall that state-sponsored hackers in China are suspected in a number of really high tech computer intrusions.
If we assume we could be moving to a Cold War 2, this puts China in a vastly different light than during Cold War 1 where no Western country would have bothered installing any critical Soviet civilian high tech infrastructure because that was an oxymoron.
Additionally, Huawei's CEO has somewhat close ties with the Chinese military and that was another red flag in this context.
Sanctions
Huawei has been put on a US entity list:
Entities on the Entity List are subject to U.S. license requirements for the export or transfer of specified items, such as some U.S. technologies.Being included on the Entities List is less severe than being designated a "Denied Person," which Chinese manufacturer ZTE was once subject to.
As a result, Huawei has been unable to procure a number of Western technological inputs, including:
the latest mobile CPUs mostly made by Qualcomm
the latest Android builds by Google
display and memory suppliers including Taiwanese and South Korean ones.
(note that what Huawei can or cannot buy is in ongoing flux as the US can and does grant licenses to trade on an exception basis)
This has had fairly negative consequences for Huawei.
From first to sixth: Huawei’s phone business tanks thanks to US sanctions