Please do let us know if you notice anything different with any masts. We have a map of the types of base stations which can be found here: https://fe326fa1-a5c1-414c-b061-20b5df03090a.filesusr.com/ugd/3e5de1_18b34e7e1c5f432980a1dd06be474923.pdf
Although there are supposedly 5G base stations in Norwich, when we visited the locations that O2 claims they are operational; we couldn't actually find any or locate them with our meter. Please do let us know if you think you spot any. If you could send a picture that would be brilliant too and we'll go over and check them out.
The chances are that your meter is telling you incorrect information, can you provide a document proving that it has been calibrated correctly? Also these meters tend to have their upper limit set at a value that is still much lower than the government's regulations.