Initialize the traffic counts with yesterday is not right because it's misleading. If one doesn't know how the package works, he/she will think that the first day had no visitors.
If the computer running the Streamlit server is in a negative timezone, altair/javascript will parse dates wrong and "shift" dates by -1 day. This Stack Overflow thread explains the issue.
See plot below to visualize the two problems:
Notice the first day is 0 and that the counting started in 27th august, but there are no pageviews in this day.
See plot below to visualize the two problems:
Notice the first day is 0 and that the counting started in 27th august, but there are no pageviews in this day.