Well… The effecrive coupling constant changes with energy. A high energy experiment behaves differently than at lower energies. The coupling constant is above 1 for the strong force at low energies, but there is ‘asymptotic freedom’ which makes it below 1 at high energies. For EM it is always below 1. I would guess they reference a ‘bare’ value here.

The purpose of these graphs are not how they look in our universe though. Rather a common way of doing anthropic style arguments. Without measuring the value of the constants, from the graph we can know from just knowing there are stable carbon and non-relativistic atoms pretty exactly where the values of the constants must be. Similar arguments can be used to pinpoint the cosmological constant from the existance of galaxies.