Not to nitpick but you're only really guaranteed privacy unless you know there's only a wired connection. If it has wifi the camera could hop onto a nearby open network and do whatever it wanted without your knowledge, assuming evil enough firmware
You can't know there's only a wired connection unless you open the camera up and inspect the PCB for an antenna, and it could still be disguised. However, by "I've only given it access to a specific network" you already eliminate 99.99% of the problem. The other 0.01% isn't really worth worrying about.
I know what you're referring to (that wifi will be so cheap and fit in a single chip that it will just phone home on open networks anyway. This was a prediction for smart TVs a few years ago) , but I think if that day comes, the devices will be easily detected and defeated by cutting the antenna or taping foil around them.
And if you're worried about threat actors on the level of backdoor/compromised firmware, the last thing you should be doing is using TP-Link Tapo cameras.
TP-Link Tapo cameras (or any other cheap cams) are fine. As long you take necessary steps to prevent leaking or calling home. I have a mix of both tapo and eufy. All of them isolated via VLAN with router FW rules set to block all traffic. The only time I had to use anything connected externally is when I had to setup each camera using the Eufy or tplink mobile apps. But once they were added to VLAN isolated wireless network, I never had to ever use the mobile app. (Unless I specifically update the firmware that addressed a problem)
