You’ll need to look at the source for the graph. Click the “3 dots” in your other graph, and you should see some option to view the JSON of the panel. Or maybe click ‘Edit’, to modify the graph. In either location, you’ll be able to see the metric names, and what unit the graph is plotting against. There could easily be a mistake in graph definition.
I can’t make any determination with what you’ve shown. Your graph shows some unknown ‘K’ unit, which somehow translates to near 100%. ‘K’ and ‘%’ are not the same.
Since I can see PMM’s source code, I know exactly where the data is coming from, and I know the unit of the graph, so I’m trusting PMM more at this time until shown otherwise.