My advice would be to switch to a Smart Shunt or Lynx Shunt. It looks like you are using a JK or Seplos BMS and those BMS-es don’t register low currents very good.
In my test setup I have a 16kwh battery with JK V19 BMS and also a 300A Victron Smartshunt. During idle (like in your situation) the JK BMS reports a current drawn from the battery of about 1,7A, which would make ik about 89 watt. However my Smartshunt is only reporting 0,3A being drawn from the battery, which is only about 16 watts.
I have confirmed this with a clamp meter, the smartshunt is correct.
Btw I am using a Multiplus II GX 48-3000 in my test setup.
