It wouldn’t be very secret if it was published on the internet. It’s definitely a credible concern given the level of control China demands of companies operating in the country. The US also essentially has backdoors into most communication, and possibly phones as well, so it’s not that crazy for China to also have them.
China is also very aggressive in hacking into companies. Even if they didn’t have a custom backdoor, them finding a way in and essentially banning Huawei from fixing it, is another option.
I was under the impression it was was common knowledge/rumor that Cisco hardware all has a US installed backdoor. Huawai having a backdoor specifically wasn’t the big revelation/concern. It was that it was Chinese/foreign government controlled. Everyone puts backdoors in, it’s just a matter of only having friendly backdoors you can control.
