Incorrect screen time on Digital Wellbeing

I check my screen time through the 'Digital Wellbeing and parental controls' option in the Settings of my MI phone. (Redmi Note 7) I manually calculated today's usage and it's around 2- 2½ hours. However, settings show 10 hr 30 min. I toggled to see the 'hourly' distribution and saw many of the apps being used at 4/5 AM. My phone was switched off during this time and I was asleep. It says I used 4 hr of YouTube today, yet the stats on the YouTube app itself says 30 mins. Is this a common bug? Or should I be concerned?