I have Canadian citizenship and lived in China when the two Michaels were locked up. In reality, even if the worst fears are true and every foreigner is explicitly tracked and constantly monitored by the local police department, it still wouldn't really be worth the government's effort to "disappear" the average foreigner, or even "invite them to tea". Most of us simply aren't that influential or important.
Of course, it does feel a bit suspicious when you say something mildly critical of the government online or during a meal with friends and then "mysteriously" the next day your VPN stops working, but it's just as likely that it could be coincidence and you're reading too much into it. But that's exactly how things are supposed to work in an authoritarian regime. Most of the time the government isn't explicitly watching over everyone, but because the legal system is deliberately opaque, everyone maintains a tiny bit of fear inside them that maybe they could be being watched, or that there might be a secret police just around the corner, so they self-censor and limit their behaviors just in case.
So, you're right that you might have anxiety the whole trip, but arguably that means you're getting to experience the "real China". Living under a constant chilling effect[0] is probably worse for locals than foreigners. At least as a foreigner you can leave when the pressure gets too much. Most locals don't have that privilege.
[0] https://en.wikipedia.org/wiki/Chilling_effect