As you see, i check on screen time in last 7 days. I choose random days. On 13th November its says 11 min. on 14th Nov - 54 min. Today if i make 5 hours on screen and i check it after 3 or 4 days will say that i use onscreen like 50 min. Btw, i think that miui screen time doesn't count onscreen time at all.