No - the company appears satisfied with OP's performance. Therefore they're not freeloading, rather they are selling the company services at the price point the company set. If someone comes to my business and we agree that I'll provide a widget for $10k, if it costs me only $1k to make it, we call that profit - i don't give them 10 widgets or a refund. A salaried job is an agreement that i will provide X KPIs, if it takes me more than 40hrs I don't get extra money, so if it takes me less an 40hrs I shouldn't give back money.

Now there may be laws or authoritarian morals around how I should lick the boots of my boss and give away more hours or outperform the KPIs, but basic capitalism says that's just a thing for suckers.