Are you running Windows 32 bit (rather than 64 bit)?
Windows 32 bit restricts to 4GB in total and, in practice, due to some overhead it never gets to 4GB (although 2.75GB seems on the low side). I typically see 3.4GB.
How to watch the Huawei Mate 30 launch live: Munich, September 19
Create live VFX
iOS 13 release date, time & new features
Comparatif : Apple Watch Series 5 vs Series 4