Battery capacity continues to be disappointing with most Google phones. They always seem to choose them on the lower-end side compared to the competition.
The phone is a good value overall, but 3,100 mAh will hardly last you one day and be almost empty by night. I prefer phones with more generous batteries, so that there's never a risk of running out by the end of the day.
Hopefully Pixel 5a will come with 4,500-5,000 mAh next year, as many low-end $200-$300 phones have these days.