I believe they are using the percentages as part of the height of the bar chart! I thought I'd seen every way someone could do dataviz wrong (particularly with a bar chart), but this one is new to me.
I take issue with their choice of bar ordering - they placed the lowest-performing model directly next to theirs to make the gap as visible as possible, and shoved the second-best model (Grok-1) as far from theirs as possible. Seems intentional to me. The more marketing tricks you pile up in a dataviz, the less trust I place in your product for sure.