This is a bit confusing and there's a lot of incorrect information out there.

The aerobic system - which gives you power for low-intensity efforts - is dual-fuel. There is a pathway where it can be fueled by glucose (glycolysis/pyruvate oxidation) and another one where it can be fueled by fatty acids (beta oxidation). Both of those paths feed into what is known variously as the Krebs cycle or the TCA cycle.

The obvious question is how the body determines whether to burn fat or glucose. It's a bit complicated.

If your blood glucose is elevated from carb intake, your body will preferentially burn glucose to try to get the blood glucose to go back down.

If blood glucose is normal, then the body will burn glucose and fat based on the kind of training you have done. Mostly high carb training, you will burn glucose. Mostly low-carb training, you will burn more fat.

At higher intensities, the additional power only comes from glucose. So a highly-trained aerobic system is better for burning fat.

So, if you want to burn a lot of fat, you need to train your body with extended periods of zone 2 training without much glucose around. Fasted is the best, but you need to transition gradually or you can run out of glucose ("bonk"), which is no fun.

This also means that the idea that you should "eat carbs to fuel your workout" is bad advice for those who want to lose weight.