iPhone 12 Pro showing weak sensitivity when doing “very gentle” tap/touch. What could be the issue?

I bought a refurbished iPhone 12 Pro yesterday, from a third party mobile shop. Since the first day, the screen does not recognise touch when I tap “very gently”. For example, when I am tapping any icon (or key) “very gently”, the touch is not recognised. I have to do proper touch always. I used iPhone (iPhone 13 brand new) before in my life during 2023 and I never faced this. The screen was very sensitive to even very tiny/mild touch. What could be the issue with my current refurbished iPhone 12 Pro? (I live in Portugal, the shop is in Portugal as well. iOS version 17.4.1)