TDD TA uses a strange scale on some Qualcomm devices

[handymenny]

Some users have reported to me a strange behavior of TA when connected to 4G TDD (specifically WindTre's B38). So I collected some data (40 points) and got this graph:

The result is that TA TDD approximate to: y = x/2 + 20.5 Where y is the TA reported by Android and x is the real TA (from baseband)

We have seen this behavior on Sony XZ1 (G8341), Xiaomi 10T (M2007J3SY), Realme GT Master (RMX3363). Note that on these same devices TA FDD = TA / 2

Can anyone else reproduce this issue?