My being one of the volunteers here doesn’t have any bearing on my perspective. I would’ve given the same response based on my experience alone, and I don’t believe that experience is entirely unique given what I’ve read from other Video Doorbell v2 users in my time here.
How did you test and confirm this? When I first installed my Video Doorbell v2 over two years ago (when I had significantly less experience with and understanding of these things), the only circuit testing I did prior to installation was checking the AC voltage across the wires where I removed the old “dumb” doorbell button to see that it was in the required 16-24 V range. I assumed that everything else had been installed correctly because that button worked with the in-place transformer and mechanical chime. I imagine a lot of users probably do the same thing, especially if things initially work as expected. Taking the time to do additional testing can be a bit of a chore and might require some degree of stubbornness persistence, but I personally feel more confident about understanding how my system is laid out and how it’s expected to work because of that additional work rather than just relying on a belief that—in my case with the pre-existing doorbell system—proved to be inaccurate.
For whatever reason (again, I’m not an electrician), my Video Doorbell v2 functioned as expected and actuated the chime for several months with the Chime Controller wired in its standard configuration. Then it got flaky and stopped unless I did something like hold in the doorbell button, but even that didn’t work 100% of the time. That’s when I reached out to Wyze Support, and they had me do some troubleshooting and eventually sent me a replacement Video Doorbell v2. While I waited for that to arrive, I decided to do my own continuity testing, and that’s how I discovered that the chime wiring was wrong before I ever started. It looked correct in the box, but I didn’t know which wires originated where until I actually traced and confirmed them, and I was able to do that with only a screwdriver, digital multimeter, and test lead. I fixed the wiring problem, reconnected Chime Controller in the standard way (the alternate wiring configuration buzz/hum drove me nuts, and I try to steer people away from doing that), and have observed that my system has worked reliably ever since.
I did set up the replacement Video Doorbell v2 and Chime Controller to confirm that those work, and then I put them back in the box and set that aside as a spare/backup. I have left my original Chime Controller in place—connected to my mechanical chime—even after swapping the Video Doorbell v2 for a Battery Video Doorbell, and that first Chime Controller is still working with my original (16 V AC, 10 VA) transformer. I don’t think the Chime Controller itself is the problem, because that has not been my experience, and I’m just sharing my experience here as other community members do with the hope that it can be helpful to others. I’m not attempting to assign blame to anyone. I’m saying that this is what has worked for me and so it may be worth trying.
I have also read about users resolving some doorbell issues by stepping up to a 16 V, 30 VA transformer, and I think that’s a solid idea, especially if the existing transformer is particularly old or if someone plans to power a second video doorbell in the same system. Wyze says repeatedly in their documentation that 16 V, 10 VA is their minimum recommendation, so I have no problem if someone wants to replace that with something else, and it’s something I considered doing when I was having problems with my own Video Doorbell v2 + Chime Controller + chime. I just found that replacement wasn’t necessary for me to resolve my issue, and I suspect that I would’ve continued to have problems even with a new transformer if I had unknowingly left my chime wired incorrectly. 
If you do replace your transformer, then I sincerely hope that resolves your issue, and I’ll be interested to read about your success. 
Regarding the QR code issue, I don’t use iOS/iPadOS, but I’ve read multiple reports here in the Forum where that can be an issue with the “Display Zoom” setting on the mobile device and getting some Wyze cameras to read it. Here’s one example: