A bootloader is a piece of code in firmware that runs when a device is powered.
Its primary function is to initialize the device’s hardware, memory, and other essential components to prepare it for the application firmware to run.
In other words, the bootloader acts as a bridge between the hardware and the main firmware, allowing the device to start up correctly and load the main software.
The bootloader can be updated only by burning the firmware with a burner (done in the factory). When a user upgrades a device via FOTA, only the application of the device is being upgraded. It does not change the bootloader version.