virtualbox – Battery decreases/increases 2% instead of 1% in Ubuntu 21.04

When I had Windows 10 my battery decreased 1% and increased 1%. So if it were plugged in after 50% it would be 51% and if it weren’t plugged in it would be 49%.
But when I switched to Ubuntu 21.04 it increases/decreases 2% each time (Rarely 3% or 1%).
I even noticed that if I use virtual machine(Windows 7 or Kali Linux) it would increase/decrease 1% each time (and that’s the real percentage of the battery).
For example, it shows 80% on both virtual machine and Ubuntu, but after that virtual machine decreases to 79% and Ubuntu stays 80% and next time they both will be 78%.