BalenaOS automatically starts ModemManager when a cellular device is connected. Some cellular modems are not compatible with ModemManager (e.g. SIM8230G) and ModemManager automatically sends spurious AT commands to them that cause them to continuously reset, meaning they are unusable.
We had to work around this by creating custom UDEV rules to mask the device from ModemManager, but it would be nice to be able to disable or configure it with an environment variable or similar setting.