I once trained a model that was performing way too well on the validation set — like, suspiciously good. At first, I was excited… but something felt off. Turned out, it was data leakage.
Here’s what I did to figure it out:

• I rechecked my data splits and found that some similar entries had ended up in both training and validation.
• I reviewed my features — one of them was indirectly revealing the target.
• I even tested a basic model, and it still performed too well, which confirmed my suspicion.

Lesson learned: if your model feels like it’s “too perfect,” always check for leakage. It’ll save you a ton of headaches later. Adopt this, It may solve this problem.