That's... not obvious at all, no? Even if it's a rando-brand, you're going to have to dig deep to show these things actually phone home. Because so far that's been a lovely little tinfoil hat conspiracy theory that just doesn't hold up to reality.

Hilariously lawful intercept^1 is a baked-in Backdoor on many US branded devices like from Cisco. It taps ports and exfils data surreptitiously.

Not just legal but legally required.

1 https://en.wikipedia.org/wiki/Lawful_interception

Only on equipment an ISP would use.

I am responding to GP's skepticism of random Chinese networking equipment in your home and their skepticism is obvious; that's what I meant. Then I proceed to explaining my own reasons at home. Now whether you agree with GP or my statements is entirely orthogonal and up for debate. There were a number of responses asking "Why?" so I took a stab at the obvious.

Sure for most people, it is a pain to dig into these things. I can negligible sometimes too. And it can be just a woo woo conspiracy in my brain, possible.

what personal data is transferred in plaintext nowadays?

really the whole "trusted/privileged network" thing is outdated. your life will be much easier if you don't trust any network.

SMB isn't encrypted by default

Maybe for ancient versions on out-of-support Windows OSes or the odd appliance but SMB has been encrypted by default since at least 2016.

In Windows 10 and 11 file sharing is strongly encrypted by default. I don't even know how to turn it off; only an option to degrade to 40bit DES for old devices.