Personal knowledge.
I can't name the phone because it never became public that this is what the fix did. They were in fact, required not to say this is what happened. You'd have to find someone willing to break the NDA (and I know a bunch of these people hang out on hacker news, so maybe you'll get it!)
However, the fact that this kind of thing is required is public knowledge through source code, so i'll repeat the link someone else posted:
Actually, I remember something very similar to this happening when one of the iPhones came out. Around the iPhone 5, IIRC.
The review sites went nuts showing the new iPhone displaying four bars while sitting next to an Android phone displaying five bars on the same carrier. The perception was that the Android had better reception, but after a short while it was revealed that the iPhone was just measuring the signal more accurately.
It was about this time that the iPhone went from displaying the traditional stepped signal bar graph to a series of dots. At the time I wondered if it was related.
However, the fact that this kind of thing is required is public knowledge through source code, so i'll repeat the link someone else posted:
https://android.googlesource.com/platform/frameworks/base/+/...
(my particular story was not about LTE, however)