UI: battery and USB icons not working properly on DIY

I noticed a difference in behaviour of the USB and battery icon among 3 DIY devices I tried:
1. M5Stick Cplus: the battery and USB icons seem to work of while both on battery and on charge.
2. M5Stick Cplus2: the USB icon is always on (even with an unconnected device) and the battery icon doesn't show the thunder when on charge.
3. M5Stack Core2: the USB icon is always on (even with an unconnected device) and the battery icon always shows the thunder, even if on battery.

1 is V1.0.31-71 which I compiled myself; 2 and 3 are V1.0.31-28 from the blockstream FW flasher site.

Because of the difference in version, I downgraded 1 to V1.0.31-28 to check if it would gain the incorrect icon behaviour.
To my surprise, when I downgraded the M5Stick Cplus using the FW flasher site, it retained the initialized status, the settings and the correct icon behaviour it had before.

The issue I'm pointing out is just graphic as far as I can check; I say that because the USB data connection with the M5 devices is not that reliable anyway and I use to go wireless.