You are welcome to reach out to Garmin Product Support in China to discuss it further. All available information on our end, when the software version in the "20.xx range", it only applies to our Fenix 6 series watches.
The highest number software versions released for the history of your Fenix 5 Plus series watch is v19.30 for all worldwide models and v17.20 for all SE Asia watches. Your watch is fully up to date. It will show v17.20 in your System > About menu.
