Buy 1GB but only get 941 MB alibaba cloud SAS? Why?

This is my first time experience with this provider. I do not get free trial so I buy 2vCPUs - 1Memory (GB) - System Disk 50GBESSD https://www.alibabacloud.com/product/swas directly.



But I only get



total        used        free      shared  buff/cache   available
Mem:         941900      109524      454064        2208      378312      686716
Swap:             0           0           0


I do not want to open ticket that will reduce my kuota. So I tried open publicly here.
Is anyone got same experience?