Once again at theses values the uni-t meter will round them sometimes, IT IS not made for these low currents values
You are trying to do things with aproximatives equipment it seems ... seeing you make some arduino or mcu projects contradicts the knowledge you need to have for precises or low values measurements
Sorry it seems harsh, but many members here gave you really solid explanations here and you need to understand them.
The equipment capacities too, you are using cheap meters to do extensive work / measurements, it kinda become stupid in a sense
threads like this will go for ever loll