Multimeter usage experience: Inaccurate measurement points

The multimeter I used was UT61E. I always thought it was quite accurate when measuring voltage and resistance. I also compared it with a 6.5-digit desktop multimeter. It felt OK, with an error of about 0.001. However, as I used it for a while, I found that it still had many shortcomings. For example, because it was in automatic mode, when measuring a resistance of 88, it could sometimes measure 0.203Ω, but it didn't always happen. When measuring a voltage near 200mv, the measurement error was really unacceptable, and there was even a situation where the values ​​of the two measurements were very different, especially when calibrating AD. This phenomenon was more obvious. For example, when you calibrate 200mv, you lower the voltage from 5V to 200mv and record the value measured by the multimeter. Then increase the voltage from 0v to 200mv and record the value measured by the multimeter. The difference between the two records will open your eyes.