Hmmm I thought that the problem was with L5. But you ask about A50. It certainly started with 4G. Now if at some point it switched to 3G, I can not be sure. Same goes for L5.
Does this imply that this test is inconclusive? the 4KHz cut is very uniform. Does it relate to 2/3/4G ?
But you know… this is typical for L5. You can hear it on the other side that it is different…