It’s not simple for the app to determine which presets are currently applied. Not impossible, but not simple – it would have to look at each preset and then look at the current state of the adjustments to see what was still valid (for example, if you apply the Red Filter Black and White Preset, but then change the amount of red, the preset is not still applied – I guess (?)). This is how Auto Enhance works – it compares the current adjustment slider positions to the ones set by Auto Enhance. If they are the same, then the auto enhance button lights up.