The graph on the left is over 4 months vs 1.5 months on the right. 1.5 months is quite short. With >1 year of data, the sharpness it is not noticeable anymore for me.
I think at some point there was an idea of an PP API to be able to adapt the design, and chart also I think. There was a recent contribution I think in issue #2478.
https://github.com/portfolio-performance/portfolio/issues/1921
https://github.com/portfolio-performance/portfolio/issues/2085
https://github.com/portfolio-performance/portfolio/pull/2478#issuecomment-2391380986
https://forum.portfolio-performance.info/t/bessere-dashboard-engine-spaltenubergreifende-widgets-beliebige-visualisierungen/19834