From your output it shows that there are two vmfs partitions

3 10229760 3907029134 AA31E02A400F11DB9590000C2911D1B8 vmfs 0

4 3907031040 11720890367 AA31E02A400F11DB9590000C2911D1B8 vmfs 0

One partition with 1.8Tb and another one with 3.8 TB.   This is the reason you are seeing only 3.8 TB

I dont know why the 1.8TB vmfs volume is not listing anywhere ( that is not listed in esxcli storage filesystem list also). Have you manually created any partition before. In case if you think there is no data in that 1.8 TB vmfs partition you can delete it using partedutil command and then use that free space to extend the existing 3.8TB. But be sure before deleting the partitiaon