I can't read the original paper, but I don't see any mention of whether they are comparing 4G to 5G NSA or 5G SA networks.
I mean, even if it were all 5G NSA, we all see the 5G label and then pay more but in reality it’s a "fake 5G", the study simply tries to understand if there is an improvement between the 5G and 4G label on the phone.
It does. It could be a hardware issue (need a new phone), software issue (e.g. OS support) or even configuration. It might not be turned on by default. I've also seen implementations where old physical sims needed be replaced.
> the study simply tries to understand if there is an improvement between the 5G and 4G label on the phone
Which misses a lot, e.g. modem changes on newer phones and bands supported, etc. As people keep buying new phones things will change.
5G NSA dramatically reduces the battery runtime. That's something users will see.
I recently was able to activate 5G NR with my provider and also my phone is compatible. The battery runtime is more that stellar now.