Unwanted factory reset WP7702

Hi,
I made an application that transmit some datas by TCP via UART1 in Linux mode.
The application worked well, until today. After a reboot, the Linux ask me to set a user and a password, like it was the first time the system boot up. All configurations done previously was erased (autosleep, warning messages,…), and the root directory (where was my application) is empty now. Did someone ever had this kind of problem ?
Here is my module configuration:
Device: WP7702
IMEISV: 6
FSN: VU027585690410
Firmware Version: SWI9X06Y_02.36.06.00 63d944 jenkins 2020/12/10 19:12:28
Bootloader Version: SWI9X06Y_02.36.06.00 63d944 jenkins 2020/12/10 19:12:28
MCU Version: 002.015
PRI Part Number (PN): 9907365
PRI Revision: 001.006
Carrier PRI Name: GENERIC
Carrier PRI Revision: 001.071_001
SKU: 1103530

Did you capture the console log in uart2?

No, only uart1 is connected

I have never seen such issue before.
But if you want to avoid legato rollback, you can see here to embed application to legato.cwe