If it recommended lower it's because of either you entering weight lifting time higher than cardio time, and as such you can safely take a deeper deficit since lifting will retain muscle mass, or you have a lot to lose.

I'm guessing if you were recommended 10% by someone, it's because you don't have much to lose or just starting out, so it's probably because of the lifting time in the activity calc.

That max deficit in 2 studies actually showed the folks gaining LBM while they lost fat and weight, eating at a steep deficit, while lifting. The study is on the TDEE Deficit tab, at the bottom, under the 0.7% loss method.

So the max deficit is based on that if lifting time is decent.

And it's a weight loss calculator, not performance. If you eat that low, you'll maintain mainly on performance while you drop fat and weight.
If just starting lifting, you'll still make improvements for a while while losing fat and weight.

So you might view that as the lowest to go, if you want better performance but slower weight loss, eat more.