Inconsistent data connection when using internet sharing

REPRODUCIBILITY (% or how often): 100%
BUILD ID = OS VERSION (Settings > About product): 4.3.0.15
HARDWARE (XA2, X10, X10 II, …): XPERIA 10 II
UI LANGUAGE: FRENCH
REGRESSION: (compared to previous public release: Yes, No, ?): Yes

DESCRIPTION:

Using a specific SIM card with operator Bouyges Telecom, I get an inconsistent connection (see attached video for more details).
This bug didn’t happen on SailfishOS 3 - See video

PRECONDITIONS:

Provider : Bouygues Telecom

STEPS TO REPRODUCE:

1 - Insert SIM card
2 - Start smartphone
3 - Enable data mobile
4 - Open Network menu (as on the video)

EXPECTED RESULT:

Stable Internet Connection

ACTUAL RESULT:

ADDITIONAL INFORMATION: