It is expected that the width of the bars at the bar chart should be wider, since currently they aren't readable. See the image below.
Every bar should start with the timestamp returned in the query response and it should continue till t+step, where t is the current timestamp and step is the value sent to the /select/logsql/stats_query_range endpoint.
Also bars should be transparent, so shorter bars aren't hidden by taller bars.
By default use bar chart for logs.