I am not sure why I am getting this error as I have specified platformName in Yaml configuration. I have run a similar test in android and it works.
Please check below:
appium --log-timestamp --session-override --base-path /wd/hub
--default-capabilities "{"usePrebuiltWDA": true, "derivedDataPath":"$DEVICEFARM_WDA_DERIVED_DATA_PATH",
"deviceName": "$DEVICEFARM_DEVICE_NAME", "platformName":"$DEVICEFARM_DEVICE_PLATFORM_NAME", "app":"$DEVICEFARM_APP_PATH",
"automationName":"XCUITest", "udid":"$DEVICEFARM_DEVICE_UDID_FOR_APPIUM", "platformVersion":"$DEVICEFARM_DEVICE_OS_VERSION",
"autoAcceptAlerts": true}"
>> $DEVICEFARM_LOG_DIR/appiumlog.txt 2>&1 &