Percentage of profits would be a terrible way to fine. Imagining how that could be messed with isn’t hard. Mysteriously there would be no profit and the follow few years worth of expenses would be pre-paid, spent or otherwise brought forward.
Sure, I don't really have any opinion on the best way to measure the size of a company. I'm just espousing the principle of scaling the fine to their ability to pay.
%of profits it fraught with ways to hide profits. Even gross revenue can be gamed, albeit with less efficacy. More practical is something like X dollars per infraction, with the ability for regulating bodies to exert some professional judgement that lets them determine if the culprit's infractions were severe enough to let the per-infraction cost put them out of business all together.