There should be a way to modify the scaling of the Y-axis when adding Timeseries/Perfstack widgets to the Modern Dashboards. Either it should automatically scale percentage metrics to 0-100% or there should be a custom option.
In the below example, if this was on a wallboard display it would look like a giant increase however getting closer the Y-axis scale is only moving roughly 5% (50% to 55%). This makes a small increase look exceptionally large from a distance.

Interestingly, if you add the same Perfstack project to a Classic Dashboard then it scales from 0-100%.

Related FRs:
Modern Dashboards - Timeseries/Perfstack widgets - Legend customisation options
Customisable timeframes on Perfstack Widgets (Classic Dashboard)